Class I-restricted cytotoxic T lymphocytes are directly cytopathic for their target cells in vivo

Although CD8-positive, class I-restricted CTL play a critical role in viral clearance and immunopathology in many model systems, they have not been shown to directly kill their target cells in vivo at the single cell level. Using a hepatitis B surface Ag transgenic mouse model of class I-restricted, CTL-mediated liver disease, we now demonstrate that CD8-positive, Ld-restricted hepatitis B surface Ag-specific CTL bind and kill their target cells in vivo by triggering them to undergo degenerative cytologic changes compatible with apoptosis. Unexpectedly, the data also indicate that the pathologic consequences of this direct, Ag-specific CTL effect are much less severe than the cytodestructive, Ag-nonspecific inflammatory response that they induce when they are activated by Ag recognition.

Accumulation of aluminum in cancers of the liver, stomach, duodenum and mammary glands of rats

The aim of the present investigation was to evaluate abnormal changes in trace element concentrations during carcinogenesis. First, Al, Zn and Cu in the liver tissues of rats were measured by atomic absorption analysis over a half year of hepatocarcinogenesis. Male Wistar rats were given carcinogenic food containing 600 mg/kg of 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) in a basal diet for several months. After 4 to 6 months of feeding, hepatocarcinomas developed in the rats. Zn and Cu concentrations in the hepatocarcinomas of the 3'-MeDAB group significantly decreased as compared with normal liver tissues of the control groups. On the other hand, the aluminum concentration in the hepatocarcinomas was more than three times that in the normal liver tissues. The Al and Se contents of developed gastric and mammary cancers were measured in Experiment II. Male and female rats were given 1-methyl-3-nitrothoguanidine(MNNG) and 2,7-dimehtylbenz(a)anthracene(DMBA), respectively. After several months, carcinomas developed in over half of the rats. The Al and Se concentrations in cancers, livers and the blood were determined by atomic absorption analysis. It was shown that both gastric and mammary carcinomas contained a high level of aluminum and very little selenium in comparison with normal liver tissues. The present study demonstrated that aluminum accumulated in experimentally induced carcinomas in rats, i.e., cancers of the liver, stomach, duodenum and mammary glands.

The mechanism of arachidonic acid release in collagen-activated human platelets

The mechanism of arachidonic acid (AA) release in collagen-activated human platelets was studied. An arachidonic acid metabolite, thromboxane B2 (TXB2), was formed in parallel with the formation of phosphatidic acid (PA) without formation of lysophosphatidic acid (lysoPA) or lysophosphatidylinositol (lysoPI) in the absence of extracellular Ca2+, suggesting that AA was released from PI via a PI-specific phospholipase C (PI-PLC)/diacylglycerol (DG) lipase/monoacylglycerol (MG) lipase pathway under the cytosolic low Ca2+ concentrations. Moreover, solubilized DG lipase and MG lipase could hydrolyze the substrates at basal cytosolic free Ca2+ concentrations. Subsequently, the relationship of cytosolic free Ca2+ concentrations and formation of AA metabolites was analyzed using Ca2+ ionophore, A23187. Collagen was able to induce a release of small amounts of AA under basal cytosolic Ca2+ conditions. However, a release of large amounts of AA was induced by phospholipase A2 activated by both collagen-receptor occupancy and elevated Ca2+ levels. A TXA2 mimetic agonist, STA2 induced all the responses except for AA release. From these results, the mechanism of AA release and signal transduction in collagen-activated human platelets is discussed.

Intraglomerular expressions of IL-1 alpha and platelet-derived growth factor (PDGF-B) mRNA in experimental immune complex-mediated glomerulonephritis

Both PDGF and IL-1 play important roles as autocrine growth factors for cultured mesangial cells, and may be closely associated with the progression of glomerulonephritis. In this study we investigated intraglomerular expressions of PDGF-B and IL-1 alpha mRNA in mice with bovine serum albumin (BSA) nephritis, a model of immune complex-mediated glomerulonephritis, using the reverse transcription-polymerase chain reaction (RT-PCR) method. We also quantified intraglomerular PDGF-B mRNA by the competitive PCR and studied the correlation between the level of intraglomerular PDGF-B mRNA expression and the degree of observed glomerular injury. While expression of neither PDGF-B nor IL-1 alpha mRNA was detected in glomeruli from control mice, both were strongly expressed in glomeruli from mice with BSA nephritis. IL-1 alpha mRNA in glomeruli showed low accumulation in mice with mild glomerular injury, and was increased in mice with moderate glomerular injury. In contrast, high intraglomerular expression of PDGF-B mRNA occurred in all mice with mild glomerular injury and continued throughout the course of the disease. We observed no correlation between the level of PDGF-B mRNA expression and the histologic grade of renal damage. These results suggest that PDGF and IL-1 have different growth properties, and PDGF might play a role as a competence factor rather than a progression factor in the pathogenesis of immune complex-mediated glomerulonephritis.

Solitary eosinophilic granuloma of bone occurring in the buccal mucosa: report of a case

Eosinophilic granuloma of bone is not uncommon in the craniofacial region (Anderson and kissane, 1977), and it sometimes occurs in organs such as the lung, stomach and spleen. However there are only few reports on solitary eosinophilic granuloma of bone occurring in oral soft tissue. In this report, we describe a case of eosinophilic granuloma of bone occurring in the soft tissue of a 40-year-old woman.

Effects of short chain fatty acid, sodium butyrate, on osteoblastic cells and osteoclastic cells

1. Sodium butyrate increased alkaline phosphatase (ALP) activity of cloned osteoblastic cell line MC3T3-E1 by the stimulation of de novo enzyme synthesis. 2. Sodium butyrate did not affect mature osteoblastic cells but affected preosteoblastic cells. 3. Sodium butyrate decreased tartrate resistant acid phosphatase (TRACP)-positive multinucleated cells (MNC) formation from bone marrow cells. This related to the cytotoxicity of sodium butyrate on bone marrow cells.

Engraftment of human non-Hodgkin lymphomas in mice with severe combined immunodeficiency

BACKGROUND

Malignant non-Hodgkin lymphoma (NHL) is one of the most difficult neoplasms to transplant into nude mice. Mice with severe combined immunodeficiency (SCID) accept various human cancers much more efficiently than do nude mice. The authors investigated whether SCID mice could be used as convenient hosts in which to grow human NHL in vivo.

METHODS

Fifty NHL specimens were engrafted into SCID mice. The original specimens and the tumors that developed in SCID mice were studied immunohistologically and by Southern blot analysis to clarify their clonal identity and to determine if they were Epstein-Barr virus (EBV)-transformed B cell proliferations.

RESULTS

SCID tumors developed from 23 of 50 NHL specimens. Ten tumors were identical immunophenotypically and, partly, genotypically to the original NHL, showing that the original NHL grew in the SCID mice. B-cell NHL rather than T-cell NHL and high-grade rather than low-grade malignancy groups were much more easily heterotransplanted. Most of the heterotransplanted NHL were maintained by successive transplantation. In two other SCID tumors, the original NHL clones and a newly developed B-cell clone coexisted. The remaining 11 SCID tumors were composed of newly developed clones. The latter 13 tumors were shown to be human cells of B-cell lineage bearing EBV latent proteins--latent membrane protein 1 and EB nuclear antigen 2--suggesting that they originated from EBV-infected B-cells that were present in the original tumor tissues.

CONCLUSION

SCID mice accept human NHL far more efficiently than do nude mice. However, frequent occurrence of spontaneous EBV-associated B-cell proliferation must be kept in mind.

HLA B44-restricted cytotoxic T lymphocytes recognizing an epitope on hepatitis C virus nucleocapsid protein

Cytotoxic T lymphocytes have been reported to be involved in the immune clearance of virus-infected cells and in the pathogenesis of viral infection. We studied the cytotoxic T lymphocyte response to the putative nucleocapsid protein of hepatitis C virus in patients with chronic hepatitis C. Cytotoxic T lymphocytes specific for hepatitis C virus nucleocapsid protein were generated from peripheral blood lymphocytes by means of repeated stimulation with a synthetic hepatitis C virus nucleocapsid protein peptide. The cytotoxic T lymphocytes were CD8 positive and recognized an epitope in hepatitis C virus nucleocapsid protein residues 81 to 100 in association with a human leukocyte antigen class I molecule, B44. The peptide-induced cytotoxic T lymphocytes recognized target cells synthesizing hepatitis C virus nucleocapsid protein endogenously, though less efficiently than peptide-pulsed target cells. The human leukocyte antigen B44-restricted cytotoxic T lymphocyte response was observed in three of five patients with chronic hepatitis C and a human leukocyte antigen B44 molecule but in neither of two hepatitis C virus-negative healthy individuals with human leukocyte antigen B44 molecules. The results demonstrate the presence of hepatitis C virus-specific cytotoxic T lymphocytes in the peripheral blood of patients with chronic hepatitis C and provide a strategy to study the role of cytotoxic T lymphocytes in the viral clearance and the pathogenesis of hepatitis C virus infection.

Mechanisms of class I restricted immunopathology. A transgenic mouse model of fulminant hepatitis

The molecular and cellular mechanisms responsible for cytotoxic T lymphocyte (CTL)-induced immunopathology are not well defined. Using a model in which hepatitis B surface antigen (HBsAg)-specific CTL cause an acute necroinflammatory liver disease in HBsAg transgenic mice, we demonstrate that class I-restricted disease pathogenesis is an orderly, multistep process that involves direct as well as indirect consequences of CTL activation. It begins (step 1) almost immediately as a direct antigen-specific CTL-target cell interaction that triggers the HBsAg-positive hepatocyte to undergo programmed cell death (apoptosis). It progresses (step 2) within hours to a focal inflammatory response in which antigen-nonspecific lymphocytes and neutrophils amplify the local cytopathic effect of the CTL. The most destructive pathogenetic function of the CTL, however, is to secrete interferon gamma when they encounter antigen in vivo, thereby activating the intrahepatic macrophage and inducing a delayed-type hypersensitivity response (step 3) that destroys the liver and kills the mouse. We propose that the principles illustrated in this study are generally applicable to other models of class I-restricted, CTL-induced immunopathology, and we suggest that they contribute to the immunopathogenesis of viral hepatitis during hepatitis B virus infection in humans.

[A case of true human tail accompanied with spinal lipoma]

Human tails have been attributed to a disturbance in fetal tail regression which normally occurs at the gestation age of about 6 weeks. To date, more than 100 cases of human tails have been reported. However, reports of true human tails, which involve the coccygeal vertebrae, are rare. We recently encountered a patient with a true human tail which involved the coccygeal vertebrae and was accompanied by lumbar spinal lipoma and spina bifida. A four-year-old boy was brought to our clinic with complaints primarily of painful mass. The boy had no neurological abnormalities. Physically, a tail bone projected, slightly in the lumbar area, with a linear depression in the center. A hard tail bone was palpable subcutaneously. A soft mass was palpable in the lumbar region, which was accompanied by hemangioma on the superficial layer of the skin in this region. On X-ray films, the tail bone lacked the normal curvature and it projected linearly in the posterior direction. CT scans revealed spina bifida at the level below L2. MRI disclosed spina bifida (at the level below L2), spinal lipoma and a tethered cord. During surgery, the tail bone was first resected over a distance of one and a half vertebral bodies. The lumbar tumor, which continued into the spinal canal, was removed as completely as possible after incision of the dura mater. To free the tethered cord, the tensioned, hypertrophic filum terminale was dissected. Although the morphological diagnosis of this condition is easy, the high incidence of complication by other anomalies makes it essential to perform thorough preoperative examinations with CT and MRI.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory effects of KW-3902, a selective adenosine A1-receptor antagonist, on the adenosine-induced shortening of action potential duration in guinea pig atrial muscles

We investigated the effects of KW-3902 (8-(noradamantan-3-yl)-1,3- dipropylxanthine), a newly-synthesized selective adenosine A1-receptor antagonist, on the shortening of action potential duration (APD) in guinea pig atria exposed to adenosine. The APD shortening by adenosine was inhibited by KW-3902 at higher than 10(-8) M, but not by 10(-5) M of KF17837, an adenosine A2-receptor antagonist. These results support the notion that the APD shortening by adenosine in atria is mediated via adenosine A1-receptors. The potency of KW-3902 in antagonizing the APD-shortening were similar to those in antagonizing the negative inotropic and chronotropic action of adenosine in the isolated right atria, suggesting that these responses to adenosine are mediated via the receptors of the same type.

[Transcranial Doppler sonography in acute intracranial hypertension model--usefulness of pulsatility index]

The authors studied intracranial hemodynamics in experimental animals (Macaca Fuscatus) with acute intracranial hypertension by use of transcranial Doppler (TCD) ultrasound. The blood mean flow velocity in the middle cerebral artery (MCA-FV) and pulsatility index (PI) was recorded using TCD ultrasound (TC2-64, EME) as in the clinical study. Acute intracranial hypertension was produced to determine the correlation of MCA-FV with intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in 11 monkeys, and the correlation of PI with ICP and CPP in 7 monkeys. ICP was elevated by infusing 0.1-0.2 ml/min of saline into the balloon using infusion pump. ICP was raised until maximum level. Changes of MCA-FV, PI, ICP and CPP were evaluated until the CPP of 0mmHg. There was a significant correlation between MCA-FV and ICP (p < 0.01) as well as between MCA-FV and CPP (p < 0.01) in all 11 monkeys. There was also a significant correlation between PI and ICP (p < 0.01) and between PI and CPP (p < 0.01) in 7 monkeys. PI increased markedly when ICP was 80mmHg or greater or when CPP was 60mmHg or less. ICP was always above 80mmHg when PI was above 1.2. All PI values were above 1.0 when CPP was 40mmHg or less. Thus, we could not estimate the absolute values of ICP or CPP from MCA-FV and PI. It seems possible, however, to follow changes in intracranial hemodynamics at the time of increased ICP if MCA-FV and PI are measured continuously while paying attention to factors influencing MCA-FV.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of rapid mannitol infusion on middle cerebral artery blood flow velocity and pulsatility index--a transcranial Doppler ultrasonography study in monkeys]

Hemodynamic changes immediately after the administration of mannitol were investigated in monkeys (Macaca Fuscata) using transcranial Doppler ultrasound (TC2-64) and were compared with those after CO2 loading. The CO2 loading group was hyperventilated to an end-tidal PCO2 of 36.5 +/- 2.21 and hypoventilated to an end-tidal PCO2 of 46.3 +/- 2.69. Mean flow velocity in the middle cerebral artery (MCA-FV), Pulsatility index (PI) and blood flow in the internal carotid artery (IC-BF) studies were performed twice before and after hypercapnea. In the Mannitol group, Mannitol (2 g/kg) was infused at a rate 20 to 30 ml/min. MCA-FV, PI, IC-BF and intracranial pressure (ICP) studies were performed twice before administration and 10 minutes after administration of Mannitol. In the Mannitol group (n = 8), MCA-FV and IC-BF and ICP increased significantly after administration of Mannitol (p < 0.005, p < 0.005, p < 0.025), but there was no significant difference in the PI. In the CO2 loading group (n = 15), MCA-FV and IC-BF increased significantly (both p < 0.005) and PI decreased significantly (p < 0.005). These results indicated that, in the presence of normal autoregulation without intracranial hypertension, there was no change in the resistance of the peripheral cerebral vessels, while a decrease in viscosity after administration of Mannitol caused an increase in cerebral blood flow. Hence, according to Poiseuille's law, peripheral vasoconstriction occurred in the early period after administration of Mannitol. This change was considered to be due to autoregulation of the cerebral vessels.

Effects of rigid gas permeable contact lens extended wear on rabbit cornea assessed by LDH activity, MDH activity, and albumin levels in tear fluid

We used noninvasive biochemical techniques to study the effects on rabbit corneas of 7-day extended wear of rigid gas permeable (RGP) contact lenses of varying oxygen transmissibilities. Corneal effects were assessed through measurement of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) activities and albumin levels in tears. The RGP contact lenses used had Dk/Ltotal values ranging from 33 to 64 x 10(-9) (cm/sec) (mL O2/mL mmHg) and were of uniform 0.15 mm center thickness. Extended wear of high Dk (Dk/Ltotal = 34) and super high Dk (Dk/Ltotal = 56) lenses caused an increase in tear LDH activity from 1,190 U/L (before lens wear) to over 18,000 U/L during 7 days of continuous wear. These contact lenses also caused gradual increases in tear MDH activity from 431 U/L (before lens wear) to over 750 U/L after 7 days of continuous wear. Extended wear of the ultra high Dk lens (Dk/Ltotal = 64), however, caused no significant increase in LDH or MDH activity in tears. Tear albumin levels in all contact lens wearing eyes increased after 1 day of lens wear, then gradually recovered to normal values after 2 days of continuous wear. The changes in albumin levels did not correlate with Dk/Ltotal values of lenses worn.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cadmium on osteogenesis within diffusion chambers by bone marrow cells: biochemical evidence of decreased bone formation capacity

The biological and biochemical effects of cadmium administration on bone marrow in rats were examined. When young adult rats were administered cadmium (Cd) repeatedly at a dose of 750 micrograms/kg body wt for up to 4 weeks, metallothionein mRNA was detected by a gene expression analysis in their bone marrow at 2 weeks after the first Cd administration, though the amounts were lower than those in liver. To determine the direct effect of cadmium on bone formation, the potential of Cd-treated bone marrow cells and demineralized bone matrix (DBM) to form bone and cartilage was assessed using a diffusion chamber (DC) in vivo, by histological examination, and by biochemical parameters such as alkaline phosphatase (ALP) activity, total calcium and phosphorus content, and the bone-specific vitamin K-dependent Gla-containing protein (BGP) content, relative to mineralization. Diffusion chambers were inoculated with DBM and bone marrow cells from either Cd-treated or nontreated rats (control) and were then implanted subcutaneously into syngeneic nontreated rats. The accumulation of BGP in DCs with Cd-treated bone marrow was significantly lower than that in control DCs. Unlike in control DC, a peak of ALP activity did not occur at 4 weeks postimplantation in DC implants inoculated with Cd-treated bone marrow; the ALP activity and calcium content in these implants were also significantly lower than those of the control bone marrow-containing chambers at the early stage of implantation. Histological examinations of chambers with Cd-treated marrow showed a decreased area of cartilage and bone foci compared with those in control chambers. These findings suggest that Cd administration inhibits the osteoblastic and chondroblastic differentiation pathway in bone marrow through direct effects on these cells.

Facial schwannoma spreading into the middle cranial fossa and the cerebellopontine angle--case report

A 53-year-old male presented with hearing impairment and facial nerve paralysis following tinnitus of the right ear. Neuroimaging revealed a tumor extensively damaging the temporal bone, and extending into the middle cranial fossa and cerebellopontine angle. The tumor was removed in a two-stage operation. The histological diagnosis was facial schwannoma.

Comparative effect of cadmium on osteoblastic cells and osteoclastic cells

Cadmium(Cd) has been thought to disturb the bone metabolism directly. The mechanism for the bone lesion is unknown, however. To examine the effects of cadmium on bone metabolism, we compared its effects on osteoblasts and osteoclasts in vitro. We used an established cell line, MC3T3-E1, as osteoblasts and tartrate resistant acid phosphatase (TRACP)-positive multi-nucleated cells (MNC) formed by a bone marrow culture system as osteoclasts. Alkaline phosphatase (ALP) activity was decreased by 10(-7) M Cd and DNA content and hydroxyproline content of osteoblastic cells were decreased by 10(-5) M Cd. Cadmium at 10(-7) M inhibited the osteoclastic cell formation from mouse bone marrow in the presence of 10(-8) M 1 alpha, 25(OH)2 vitamin D3. A 100-fold higher concentration of zinc(Zn) simultaneously added to the cadmium-containing medium prevented the toxicity of cadmium to osteoclastic cells as observed in the culture of osteoblastic cells. These results indicate that both bone formation and bone resorption are inhibited by cadmium. The responses of osteoclasts and osteoblasts to cadmium in this culture system were the same and the responses of cadmium-damaged osteoblasts and osteoclasts to zinc were also similar. These results suggest that another mechanism by which cadmium could cause bone damage should be considered in addition to the specific induction of osteoclastic cells by Cd.

Verucopeptin, a new antitumor antibiotic active against B16 melanoma. II. Structure determination

The structure of a new antibiotic verucopeptin has been determined by the spectroscopic analyses and chemical degradation studies. It is a 19-membered cyclodepsipeptide which is structurally related to azinothricin and A83586C.

1,4:3,6-Dianhydrohexitol nitrate derivatives. II. Synthesis and antianginal activity of aryl- or arylcarbonylpiperazine derivatives

A series of 5-(4-aryl- or 4-arylcarbonylpiperazin-1-yl)-5-deoxy-1,4: 3,6-dianhydro-L-iditol 2-nitrates was prepared in order to obtain orally active, nitrate-type vasodilators with reduced side effects. Our drug design was based on a small reduction in the lipophilicity compared to that of 5-deoxy-5-[4-(3-phenylthiopropyl)piperazin-1-yl]-1,4: 3,6-dianhydro-L-iditol 2-nitrate (1, KF14124). Compounds 4h (aryl = benzimidazol-2-yl), 4i (arylcarbonyl = nicotinoyl), and 4w (arylcarbonyl = 3-furoyl) showed potent anti-ischemic activity in a lysine-vasopressin-induced angina pectoris model (rats), and their structure-activity relationships are discussed. Compound 4i exhibited potent vasodilation of the coronary artery in anesthetized dogs and also exhibited potent preload reduction in a heart failure model (dogs) as compared with isosorbide dinitrate (2), nicorandil (3), and KF14124 (1). Furthermore, 4i showed much weaker acute lethal toxicity and less central nervous system depression than 1 in mice. Thus, 4i (KW-3196) is under development as a vasodilator and a drug for treating angina pectoris.

Synthesis and antifungal activity of pradimicin derivatives. Modifications of the sugar part

Modifications at the sugar part of pradimicins were carried out by glycosidations of the aglycones or chemical transformations of natural pradimicins and their antifungal activity was evaluated. Among them, some of the D-xylose-modified derivatives (14, 17, 24) showed activity comparable to that of pradimicin A. The structure-activity relationships obtained through there studies clarified the role of the sugar part in the manifestation of antifungal activity: The 5-O-(6-deoxy-beta-D-sugar) is essential for activity and 2'-epi, 3'-oxo and 4'-deoxy sugar derivatives retain activity against yeasts.

[Elevation of serum apo E-rich HDL concentration in a patient with cholestatic liver disease]

A remarkable elevation of serum HDL cholesterol concentration (165mg/dl) was found in a 42-year-old Japanese male with chronic pancreatitis who had been cholestatic for several years. An abnormal slow alpha-migrating lipoprotein, larger in particle size and more enriched with cholesteryl ester and apo E than normal HDL, was found in the patient's plasma. Quantitative determination of apo E-rich HDL revealed a striking increase of this lipoprotein in plasma. After choledocho-jejunostomy, a prompt and remarkable decrease of plasma apo E-rich HDL was observed, indicating a direct contribution of cholestasis to the accumulation of apo E-rich HDL in plasma in this patient.

Correlation between lack of bone Gla protein mRNA expression in rat transplantable osteosarcomas and expression of both c-fos and c-jun proto-oncogenes

Alkaline phosphatase (AP) activity and expression of bone Gla protein (BGP), c-fos, and c-jun were compared in two transplantable osteosarcomas with high potentials for metastasis to the lung. The original spontaneous osteosarcoma (SOS) gradually became histologically undifferentiated, losing its osteogenic activity during serial transfer, whereas the chemical (4-hydroxyaminoquinoline 1-oxide)-induced osteosarcoma (COS) retained osteogenesis. The two osteosarcomas showed similar doubling times and levels of lung metastasis, and strong AP activity was detected on the cell membranes of both. Northern blot analysis revealed that lack of BGP mRNA expression was associated with expression of both c-fos and c-jun proto-oncogenes in SOS. In contrast, neither c-fos nor c-jun mRNAs were detected but BGP mRNA was expressed in the case of COS. These results suggest that the c-fos and c-jun genes may suppress the expression of BGP mRNA relevant to differentiation and osteoid formation in rat osteosarcomas. However, this does not appear to be directly related to proliferative or metastatic biological behavior.

Calcium channel blocker-like action of reserpine in smooth muscle

The effect of reserpine on vascular and intestinal smooth muscles was examined. In these muscles, reserpine inhibited the high K(+)-induced contraction, and this inhibitory effect was antagonized by the increase in external Ca2+ concentration and also by a Ca2+ channel activator, Bay k8644. In rabbit aorta, increases in cytosolic Ca2+ level and muscle tension due to high K+ were inhibited in parallel by reserpine. These results suggest that reserpine inhibits L-type Ca2+ channels to inhibit smooth muscle contraction.

Spatio-temporal pattern of frequency representation in the auditory cortex of guinea pigs

The spatio-temporal pattern of sound-evoked neural activity in the guinea pig auditory cortex was studied by optical recording with the aid of voltage-sensitive dye. Changes in light intensity induced by sounds at various frequencies and pressure levels were recorded with a 12 x 12 array of photodiodes. The amplitudes of the responses were displayed as sequential two-dimensional images. Tonotopical organization was found in two subdivisions of the auditory cortex, the anterior field (field A) and the dorsocaudal field (field DC). The frequency gradients in fields A and DC had a mirror-image relationship. This agrees with results obtained by the microelectrode technique. However, the tonotopic response observed in our study was transient. The focal activity that began in field A propagated in two directions; dorsally along the iso-frequency bands in field A, and caudally toward field DC. This suggests that the sound information processing initiates at field A, and its outputs are transferred to field DC, which is probably a hierarchically higher center.

cDNA cloning of rat LRP, a receptor like protein tyrosine phosphatase, and evidence for its gene regulation in cultured rat mesangial cells

Protein tyrosine phosphatases (PTPases) are a family of enzymes that play a crucial role in the regulation of signal transduction mediated by reversible protein tyrosine phosphorylation. To understand the significance of PTPases in physiological and pathophysiological processes in the kidney, we isolated three cDNA segments encoding PTPases (LAR, LRP and a novel PTPase) from rat kidney by polymerase chain reaction (PCR). Using PCR product as a probe, we isolated a full-length cDNA of rat LRP. LRP cDNA encoded a single membrane spanning protein consisted of 796 amino acids, with two tandemly located intracellular PTPase domains. By Northern analysis, a ubiquitous pattern of LRP gene expression in rat tissues was demonstrated. In cultured rat mesangial cells, LRP mRNA was detected and the mRNA level was suppressed by either interleukin-1 or interleukin-6 treatment.