Structural and functional analysis of the canine histamine H2 receptor by site-directed mutagenesis: N-glycosylation is not vital for its action

G-protein-coupled receptors generally share a similar structure containing seven membrane-spanning domains and extracellular site(s) for N-glycosylation. The histamine H2 receptor is a member of the family of G-protein-coupled receptors, and has three extracellular potential sites for N-glycosylation (Asn-4, Asn-162 and Asn-168). To date, however, no information has been presented regarding N-glycosylation of the H2 receptor. To investigate the presence, location and functional roles of N-glycosylation of the H2 receptor, site-directed mutagenesis was performed to eliminate the potential site(s) for N-glycosylation singly and collectively. The wild-type and mutated H2 receptors were expressed stably in Chinese hamster ovary (CHO) cells or transiently in COS7 cells. Immunoblotting of the wild-type and mutated H2 receptors with an antiserum directed against the C-terminus of the H2 receptor showed that mutation at Asn-162, but not at Asn-168, resulted in a substantial decrease in the molecular mass. A mutation at Asn-4 led to a further decrease in the molecular mass. Tunicamycin treatment of the transfected cells yielded a sharp band with a molecular mass identical to that of the mutant devoid of all three potential sites for N-glycosylation. These findings indicate that the H2 receptor is N-glycosylated, and that N-glycosylation takes place mainly at two sites, Asn-4 and Asn-162. Neither the affinity for tiotidine nor that for histamine was affected by the mutagenesis. Immunocytochemistry and tiotidine binding showed that the mutated receptors were exclusively distributed on the cell surface in a fashion similar to that of the wild-type. In addition, the glycosylation-defective receptor was capable of activating adenylate cyclase and elevating the intracellular Ca2+ concentration in response to histamine in stable CHO cell lines. Thus N-glycosylation of the H2 receptor is not required for cell surface localization, ligand binding or functional coupling to G-protein(s).

Modulation of the stress-induced synthesis of stress proteins by a phorbol ester and okadaic acid

The expression of alphaB crystallin, hsp27, and hsp70 in C6 cells increased when they were exposed to arsenite (50 microM for 1 h) or heat (42 degrees C for 30 min), as detected by specific immunoassays, Western blot analysis, and Northern blot analysis. When cells were exposed to arsenite in the presence of 0.1 microM phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, or 0.2 microM okadaic acid, an inhibitor of phosphoserine/phosphothreonine protein phosphatases, expression of alphaB crystallin was markedly enhanced. The induction of hsp27 and hosp70 expression was also stimulated to a considerable extent in the same cells. The stimulatory effect of PMA was further enhanced in the presence of okadaic acid, but it was strongly inhibited in the presence of 0.5 microM staurosporine, an inhibitor of protein kinase C. PMA and okadaic acid also stimulated the response to heat stress of the expression of alphaB crystallin, but they barely stimulated the response to heat stress of hsp27. The extent of stimulation of the arsenite-induced responses by PMA and okadaic acid was greater when the concentration of arsenite (i.e. the magnitude of the stress) was relatively low (25-50 microM). The arsenite-induced release of arachidonic acid from cells was also stimulated in the presence of PMA and/or akadaic acid, and the stimulatory effects of PMA and okadaic acid on the arsenite-induced accumulation of alphaB crystallin and hsp27 were strongly suppressed by quinacrine, an inhibitor of phospholipase A2. These results suggest that the stimulatory effects of PMA and okadaicacid on the stress responses are cuased, in part, by the increased metabolic activity of the arachidonic acid cascade, as a consequence of the activation of phospholipase A.

Enhancement of the antitumor effect by combined use of high-energy shock waves and ATX-70

The antitumor effects of high-energy shock waves (HESW) in combination with ATX-70 [a gallium-porphyrin complex, 2,4-bis(1-decyloxyethyl)-Ga(III)-1,3,5,8-tetramethylporphyrin++ +-6, 7-dipropionyl diaspartic acid [sequence: see text] were investigated. In vitro, the cell damage to mouse MH134 hepatoma after HESW treatment was enhanced by adding ATX-70. In vivo, HESW and ATX-70 combination therapy inhibited cell growth. However, neither HESW treatment alone nor ATX-70 treatment alone inhibited cell growth. These results imply that the antitumor effects of HESW and ATX-70 combined therapy are caused by activation of ATX-70 by HESW.

The structure and function of p55PIK reveal a new regulatory subunit for phosphatidylinositol 3-kinase

Phosphatidylinositol 3-kinase (PI-3 kinase) is implicated in the regulation of diverse cellular processes, including insulin-stimulated glucose transport. PI-3 kinase is composed of a 110-kDa catalytic subunit and an 85-kDa regulatory subunit. Here, we describe p55PIK, a new regulatory subunit that was isolated by screening expression libraries with tyrosine-phosphorylated insulin receptor substrate 1 (IRS-1). p55PIK is composed of a unique 30-residue NH2 terminus followed by a proline-rich motif and two Src homology 2 (SH2) domains with significant sequence identify to those in p85. p55PIK mRNA is expressed early during development, remains abundant in adult mouse brain and testis tissue, and is detectable in adult adipocytes and heart and kidney tissues. p55PIK forms a stable complex with p110, and it associates with IRS-1 during insulin stimulation. Moreover, the activated insulin receptor phosphorylates p55PIK in Sf9 cells, and insulin stimulates p55PIK phosphorylation in CHOIR/p55PIK cells. The unique features of p55PIK suggest that it is important in receptor signaling.

[A study of the intraorbital blood flow using ultrasound color Doppler mapping images in optic canal fracture cases]

Ultrasound color Doppler flow mapping image (CFMI) equipment, SSA-270A (Toshiba Co) was used to measure the blood flow velocity of the ophthalmic artery (OA) and the central retinal artery (CA) in eyes with optic canal fracture. The maximal blood flow velocity (V max), the minimal blood flow velocity (V min), the mean blood flow velocity (V mean), and the resistance index (RI) before and after transethmoidal decompression of the optic nerve were compared. The examination was conducted on 13 patients. There was no difference in blood flow velocity in the CA after the operation. Pre-operative V max and RI of the OA in the damaged eyes were lower than in normal eyes, but they increased the day after the operation. We measured the intraorbital blood flow velocity by CFMI because ultrasound does not penetrate bone. Since the peripheral artery from the optic foramen did not change after the operation, we concluded that the peripheral blood flow of OA had been quantitatively improved by the trans-ethmoidal decompression of the optic nerve.

Enhancement of stress-induced synthesis of stress proteins by mastoparan in C6 rat glioma cells

The levels of two small stress proteins, hsp27 and alpha B crystallin, were low in C6 glioma cells confluency. However, the levels of the two proteins increased after exposure of cells to heat (42 degrees C for 30 min) or arsenite (50-100 microM for 1 h) stress. When cells were exposed to arsenite or heat in the presence of mastoparan, a peptide toxin from wasp venom, the induction of hsp27 and alpha B crystallin was markedly stimulated, as detected by means of specific immunoassays, Western blot analysis, and Northern blot analysis. The response of hsp70 to each stress was also enhanced in the presence of mastoparan. Treatment of cells with 40 microM mastoparan alone barely induced the accumulation of hsp27 and alpha B crystallin. The stimulatory effect of mastoparan was little affected in cells that had been treated with pertussis toxin, but it was strongly suppressed in the presence of quinacrine, an inhibitor of phospholipase A2. These results suggest that mastoparan, which is an activator of phospholipase A2, enhances the responses to stress of hsp27, alpha B crystallin and hsp70 by increasing the metabolic activity of the arachidonic acid cascade.

[MR angiography of the venous system of lower extremities with gadolinium-enhanced fast spoiled GRASS]

MR angiography (MRA) of the venous system of the lower extremities was carried out in 10 patients with varicose veins using the Gd-DTPA-enhanced Fast Spoiled GRASS (FSPGR) method. The quality of imaging of the popliteal vein (n = 20), calf deep vein (n = 20), varicose vein (n = 12), and femoral vein (n = 6) were assessed in terms of four categories: excellent, good, marginally adequate and nondiagnostic. Nineteen popliteal veins, seventeen calf deep veins, and nine varicose veins were judged as excellent or good. All femoral veins were evaluated as excellent. Enhanced FSPGR was useful for the preoperative evaluation of patients with varicose veins.

Frequent p53 accumulation in the chronically sun-exposed epidermis and clonal expansion of p53 mutant cells in the epidermis adjacent to basal cell carcinoma

p53 expression was studied immunohistochemically to identify a precursor lesion of basal cell carcinoma (BCC) in the epidermis adjacent to BCC. With two different anti-p53 antibodies of CM1 and DO7, p53 expression was frequently detected in the epidermis adjacent to BCCs arising on the face and in the normal epidermis with usual sun exposure. In the epidermis adjacent to BCC, stained cells were occasionally clustered in a small area, but no cluster was found in the normal epidermis with usual sun exposure. The expression was less frequent in the normal epidermis with rare sun exposure. Ten cases of normal skin with usual sun exposure, showing CM1 staining in the epidermis, were screened for p53 gene mutations with polymerase chain reaction-single-strand conformation polymorphism analysis using DNAs obtained from the epidermis. No mutation was detected in exons 2 to 10 of the p53 gene in these 10 cases. The epidermis flanking three BCCs that was stained with CM1, on the other hand, carried a missense mutation of C to G transversion at a dipyrimidine site of codon 249. This alteration replaced arginine with threonine. The mutation of codon 249 was not detected in the three BCCs. Our results first suggest that ultraviolet light irradiating the skin in a daily life induces p53 accumulation in the epidermis and secondly that the frequent clonal expansion of p53 mutant cells occurs in the epidermis adjacent to BCCs. This clonal expansion of mutant p53 may provide a molecular basis for high risk of developing subsequent new skin cancers in patients with BCC.

[Study of serial bronchoalveolar lavage in patients with aspergilloma: cell reaction at the affected sites and penetration of miconazole and flucytosine into the lesion]

We have performed serial bronchoalveolar lavage (BAL) examination in two patients with asperigilloma and compared that of total cell count and cell population with control groups (5 non-smokers, 10 smokers) and other pulmonary infectious diseases: 7 each with mycoplasmal pneumonia and pulmonary tuberculosis, 6 with bacterial pneumonia, and 5 with chlamydial pneumonia. Miconazole (MCZ) by drip intravenous infusion of 400 mg/day and flucytosine (5-FC) by oral intake of 4.5 to 6.0 g/day were administered to one patient with aspergilloma, and we studied the serum and BALF concentration about 5 hours after administration. The followings results were obtained: 1. In aspergilloma, the cell population of neutrophils in BALF increased compared with control groups (p < 0.01) and other pulmonary infectious disease. 2. The serum and BALF levels of MCZ ranged from 0.1 to 0.3 micrograms/ml, < 0.1 14.4 micrograms/ml, respectively. On the other hand, the serum and BALF levels of 5-FC ranged from < 0.2 to 9.3 micrograms/ml, and < 0.4 to 1.5 micrograms/ml, respectively. From these results, we consider that neutrophils play the main role in the immune host defense in aspergilloma, and the combination of intracavitary infusion of MCZ and oral administration of 5-FC should be the treatment of choice.

Peroxidase activity and cell differentiation in developing salivary glands of the rats

Peroxidase (PO) activity-positive cells were found to develop in both the sublingual and submandibular glands of the rat on day 19 of gestation. The PO activity in the nuclear envelope (NE), endoplasmic reticulum (ER), Golgi apparatus (G) and secretory granules (SG) of these cells were enhanced day by day. However, no PO activity was detected in the parotid gland on the same day. In the parotid gland PO-positive cells were detected first on postnatal day 1. After birth the PO activity in the SG of both the sublingual and submandibular glands gradually diminished in intensity and disappeared, whereas the activity persisted in the parotid gland. From postnatal day 1 to 14, the NE and ER of the cells in the parotid and sublingual glands exhibited intense PO activity, while cells containing mucous SG appeared. The cells were identified as mucoserous acinar cells. These mucoserous cells later differentiated into different cell types: serous cells in the parotid gland and mucous cells in the sublingual gland. As the submandibular gland developed, PO activity-positive serous cells also differentiated into mucoserous cells and the activity in the G and SG disappeared. The parotid, sublingual and submandibular glands of perinatal rats have clearly showed varied growth, with the advent processes of PO activity and cell differentiation, whereas PO activity in the G concomitantly occurred with SG activity.

Early ultrastructural glomerular alterations in neonatal nephrotic mice (ICGN strain)

ICGN is a strain of mice with hereditary nephrotic syndrome of an unknown cause. In this study, early glomerular alterations in newborn ICGN mice were observed with electron microscopy to gain a better insight into the onset of the disease. Development of the glomeruli was normal until fusion of epithelial and endothelial basement membranes in the developing capillary stage. From the maturing glomerulus stage onward, the fused glomerular basement membrane (GBM) increased in thickness by excessive accumulation of the basement membrane material secreted from the epithelial cells. This accumulation was followed by overall loss of epithelial foot processes in the glomeruli. These findings indicate that the disease in ICGN mice is caused by some defect(s) in the GMB maturation process, which may be crucial for the generation of the glomerular permselectivity.

A recurrent case of spontaneous mediastinal emphysema

The first case of spontaneous mediastinal emphysema was reported by Hamman et al. in 1939. It is a rare condition that primarily occurs in young adults. In many instances, spontaneous mediastinal emphysema is caused by yelling, shouting or active exercise, but the cause is often unknown. It is rare for cases of spontaneous mediastinal emphysema to recur. Recently, we experienced a recurrent case of spontaneous mediastinal emphysema in a patient with a duodenal ulcer. Vomiting appeared to be the cause of the recurrence in our patient. Of the 58 patients with spontaneous mediastinal emphysema who have been reported in Japan so far, recurrences were documented only in our patient and two others.

[Highlateral approach to the lesions around the upper cervical vertebrae and foramen magnum]

In the present paper, we describe the surgical techniques of high lateral cervical approach and its feasibility for the excision of tumors located in the ventral or lateral aspect of the upper cervical vertebrae and of the craniovertebral junction. The patient is positioned laterally on the operating table, but the operator's position and the skin incision are slightly altered depending on the location of the tumor. When the lesion is situated below C1, the ipsilateral shoulder is pulled down toward the back. The operator stands rostral to the head. The attachment of the sternocleidomastoid muscle to the mastoid is detached and reflected anteriorly through a retroauricular curved skin incision. The posterior cervical muscles such as the splenius capitis, longissimus capitis, semi-spinalis capitis are detached from the occipit and retracted posteriorly. At this point, the transverse process of C1 and the articular facet of the vertebrae of C2-C4 are identified by palpation. According to the tumor location, the muscles attached to the relevant transverse processes and facets are divided and reflected posteriorly. Through careful dissection, the cervical nerve roots and the vertebral artery are exposed. The root sleeves as well as thecal sac may be exposed by resecting the posterior two-thirds of the superior and inferior articular facets and the adjacent laminae of the vertebrae. In case the whole facet was removed, an iliac bone graft is placed between the remaining transverse processes and the laminae above and below for fixation.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological studies on the kidney of the spontaneous nephrotic (ICGN) mice in the late stage

Spontaneous nephrotic (ICGN) mice develop proteinuria, hypoproteinemia and hypercholesterolemia. These symptoms steadily progress to chronic renal failure. Details of the changes of the kidney, in the late stage (more than 5 months old) were investigated by both light and electron microscopy. The kidney exhibited a slightly whitish, granular surface and the cortex became thinner and contained fibrous lesions, in which clusters of unaffected and occluded renal tubules were randomly scattered. In the juxtamedullary and outer medullary zone, there were highly dilated renal tubules, which sometimes contained urinary casts. The glomerulus exhibited basement membrane thickening in the capillary loops and the capillary lumen was narrowed in size and sometimes occluded. No detachment of the podocyte from the basement membrane was observed and the podocyte foot-processes were extensively fused, causing their characteristic slits to be lost. The thickened basement membranes were found both in the glomerulus and around the occluded renal tubules, while the basement membrane in the dilated renal tubule appeared normal. Therefore, the basement membranes of the glomerulus and renal tubules appear to react differently in the pathogenesis of the condition. In conclusion, ICGN mice are a good model for not only the nephrotic syndrome but also for chronic renal failure.

ATP-evoked membrane current in guinea pig adrenal chromaffin cells

Adenosine 5'-triphosphate (ATP) evoked an inward current in whole-cell voltage-clamped adrenal chromaffin cells of the guinea pig. The reversal potential (Erev) of ATP-evoked current was about 0 mV in normal external solution and was shifted towards negative potentials by substituting Tris+ or sucrose, but not Ca2+, for the extracellular Na+. This current was mediated by the activation of non-selective cation channels and had some different properties from nicotinic current. It is suggested that these channels may function as a part of the ATP-induced Ca2+ influx pathway in guinea pig chromaffin cells.

[Perinodal cryomodification for supraventricular tachycardia]

The perinodal cryomodification procedure ablates the surrounding tissue of atrioventricular node, as a consequence, eliminates atrioventricular nodal reentrant tachycardia (AVNRT) and reduces the ventricular response during atrial fibrillation. We performed the procedure in 4 patients: 2 patients with AVNRT, 1 patient with atrioventricular reciprocating tachycardia utilizing a left side accessory pathway and atrioventricular node dual pathways, and 1 patient with tachycardic atrial fibrillation. The concomitant procedures include a closure of atrial septal defect and a mitral valve replacement. All the patients survived the procedure and cured the tachycardia. Post operative electrophysiological studies showed that the retrograde conduction over the atrioventricular node was eliminated while the antegrade conduction was preserved in the patients with atrioventricular node dual pathways. The perinodal cryomodification is a safe and effective procedure to cure the tachycardia, particularly in the patients with a structural heart disease.

Localization of various forms of the gamma subunit of G protein in neural and nonneural tissues

For a study of the localization of various forms of the gamma subunit of G proteins, antibodies were raised in rabbits against peptides that corresponded to partial amino acid sequences of bovine gamma 2, gamma 3, gamma 5, and gamma 7. Affinity-purified antibodies against gamma 2, gamma 3, and gamma 5 reacted specifically with gamma 2, gamma 3, and gamma 5, respectively, but the antibody against gamma 7 reacted with gamma 2, gamma 3, and a novel gamma subunit, designated gamma S1, as well as with gamma 7. Because these antibodies reacted with the respective forms of the gamma subunit from rat brain, we investigated the localization of gamma subunits in the rat. gamma 2 and gamma 3 were abundant in all regions in the brain, whereas the concentration of gamma 5 and gamma 7 was relatively low with the single exception being a high concentration of gamma 7 in the striatum. The concentration of gamma 2 was consistently high during ontogenic development in the rat brain, whereas gamma 3 appeared about a week after birth and their concentrations then increased until a month after birth. In tissues other than the brain, gamma 3 was observed only in the pituitary gland, whereas gamma 2, gamma 5, and gamma 7 were found in a variety of tissues. In addition, most tissues contained relatively high concentrations of some other gamma subunit, which was detected with an antibody against a gamma 7-derived peptide and appeared to be gamma S1. Among cloned cells tested, gamma 3 was detected only in PC12 pheochromocytoma cells.(ABSTRACT TRUNCATED AT 250 WORDS)

[Study on tumor accumulation property of 99mTc-HM-PAO and 99mTc-MIBI in rabbits bearing VX-2 cancer]

Each of blood flow imaging agents has a potential usefulness as an agent for tumor scintigraphy. The usefulness for tumor scintigraphy of two agents, i.e. cerebral blood flow scintigraphy agent 99mTc-HM-PAO and myocardial blood flow scintigraphy agent 99mTc-MIBI, was comparatively studied using rabbits bearing VX-2 cancer. From then to twenty days after the implantation of VX-2 cancer into the femoral region of five rabbits, tumor to soft tissue accumulation ratio (T/S ratio) of each agent was calculated in early images (5 min after injection) and in late images (50 min after injection). Compared with 99mTc-MIBI, the T/S ratio of 99mTc-HM-PAO was higher and, moreover, the washout was delayed. These results suggest that there is a difference in tumor accumulation property between these two agents.

Rare association of human papillomavirus DNA with esophageal cancer in Japan

To examine whether human papillomavirus (HPV) DNA is associated with esophageal cancer, frozen and paraffin-embedded neoplasms of the upper aerodigestive tract, including esophageal cancer, were investigated. DNA obtained from frozen specimens and cell lines were analyzed by both polymerase chain reaction (PCR) and Southern blot hybridization. DNA from paraffin-embedded samples were analyzed strictly by PCR. DNA of HPV types 6 and 11 was detected in papillomas of the upper respiratory tract at > 50%. However, HPV DNA was infrequently detected in specimens from the upper digestive tract (31 esophageal cancers and 2 esophageal carcinoma--derived cell lines), even by PCR at a sensitivity of 0.1 copy number per cell. These results suggest that the etiologic significance of HPV infection in esophageal cancer is negligible.

[Anterior transcallosal approach for the mass lesions in and around the third ventricle: with particular reference to the method of enlarging the foramen of Monro]

Enlargement of the foramen of Monro is an essential maneuver to obtain an appropriate surgical view when large, solid lesions in and around the third ventricle are to be removed via the anterior transcallosal approach (ATA). For this purpose, three methods, i.e., the subchoroidal, transchororidal, and transfornicial approaches have so far been reported. However, since the locations and the pathological natures of space occupying lesions in this region are widely variable, the indication as well as the feasibility of each approach has remained rather unclear. The present paper deals with our surgical experience with six patients (2 gliomas, 1 angioma, 1 AVM, 1 plexus papilloma, 1 basilar top aneurysm) operated on using the ATA in which variable methods of enlarging the foramen of Monro were employed. Aiming at complete removal or clipping of the lesion, the seemingly best among the above three approaches was determined preoperatively, considering the size, location, and pathological nature of the lesion. The shape of the choroid plexus of the roof of the IIIrd ventricle as revealed by MRI was also taken into account. The subchoroidal, transchoroidal, and the transfornicial approaches were employed in 3, 2, and 1 cases, respectively. Except for one glioma which ended up being removed extensively, all the tumors and AVM were totally removed and the aneurysm successfully clipped. From the above experience, the merits and demerits of each approach for different types of lesions are discussed in view of their suitability for achieving total removal.(ABSTRACT TRUNCATED AT 250 WORDS)