Transconjunctival immunotherapy using cholera toxin B to treat experimental allergic conjunctivitis in a mouse model

PURPOSE

We evaluated the use of immunological biomarkers in transconjunctival immunotherapy by using cholera toxin B for treating experimental allergic conjunctivitis in a mouse model.

METHODS

Balb/c mice were sensitized using intraperitoneal injections of ovalbumin (OVA) and were then divided into two groups. The first group was treated by topical instillation of OVA after the instillation of combined OVA and cholera toxin B (CTB) solution B group). The second group was treated by topical instillation of OVA alone (allergy group). The control group consisted of nonsensitized mice undergoing topical OVA instillation only. The numbers of eosinophils and CD4-positive lymphocytes in the conjunctiva were determined histologically, and the observation of immunoglobulin A (IgA)-positive cells in the conjunctiva was performed by immunohistochemistry. Cytokine concentration in the conjunctiva was determined by the protein-array methods. Messenger RNA expression of T-cell-specific markers, such as T-bet, GATA-3, and Foxp3, in the conjunctiva was detected by reversed transcriptase polymerase chain reaction.

RESULTS

The number of eosinophils and CD4-positive lymphocytes increased significantly in the allergy group compared with the control group (P < 0.001) but showed no difference between the CTB group and control group. Concentrations of interleukin 4 (IL-4) (P < 0.05), B-lymphocyte chemoattractant (P < 0.01), and thymus-expressed chemokine (P < 0.05) in the conjunctiva were significantly higher in the CTB group than in the other two groups. GATA-3 messenger RNA (mRNA) in the conjunctiva was expressed in the three groups, but T-bet and Foxp3 were not detected.

CONCLUSION

Transconjunctival immunotherapy using CTB can be evaluated by histological examination of eosinophils and CD4-positive T cells, and a mucosal immunity-associated chemokine and a helper T-cell-17-associated chemokine as biomarkers.

[Case of pediatric chronic myeloid leukemia with bilateral visual loss onset]

BACKGROUND

Chronic myeloid leukemia (CML) during childhood is rare, and only been a few cases showed visual disturbances as an initial symptom. We report a pediatric CML case diagnosed by bilateral visual loss.

CASE

An 11-year-old boy complained of visual loss in both eyes. His best corrected visual acuity was 0.5 in the right eye and 0.2 in the left. Fundus examination showed disc swelling, dilated and tortuous retinal veins and multiple elevated retinal lesions with hemorrhages of various size from one-forth to four disc diameters in both eyes. He was diagnosed as having CML by leucocytosis and systematic work-up including Philadelphia chromosome-positive, BCR-ABL kinase domain in peripheral blood and bone marrow. The ocular findings improved after treatment with hydroxyurea, leukocytaphresis and imatinib. His best corrected visual acuity improved to 0.7 in both eyes.

CONCLUSION

Recent leukemia therapy including imatinib is effective not only for ocular lesions but also to induce hematological remission in childhood CML.

Mitogen-activated protein kinases mediate interleukin-1?-induced receptor activator of nuclear factor-?B ligand expression in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Interleukin-1beta-stimulated receptor activator of nuclear factor-kappaB ligand (RANKL) expression in human periodontal ligament cells is partially mediated by endogenous prostaglandin E2, whereas mitogen-activated protein kinases (MAPKs) are implicated in regulating various interleukin-1-responsive genes. We investigated herein the involvement of MAPKs in interleukin-1beta-stimulated RANKL expression in human periodontal ligament cells.

MATERIAL AND METHODS

Human periodontal ligament cells were pretreated separately with specific inhibitors of MAPKs, including extracellular signal-regulated kinase, p38 MAPK and c-Jun N-terminal kinase, and subsequently treated with interleukin-1beta. Following each treatment, the phosphorylation of each MAPK, the expression of RANKL, and the production of prostaglandin E2 were determined. RANKL activity was evaluated using an assay to determine the survival of prefusion osteoclasts.

RESULTS

Interleukin-1beta induced RANKL expression at the mRNA and protein levels, as well as RANKL activity in human periodontal ligament cells. Interleukin-1beta also activated extracellular signal-regulated kinase, p38 MAPK, and c-Jun N-terminal kinase. Pretreatment with each MAPK inhibitor partially, but significantly, suppressed interleukin-1beta-induced RANKL expression and its activity, as well as prostaglandin E2 production.

CONCLUSION

In human periodontal ligament cells, three types of MAPK inhibitor may abrogate RANKL expression and activity induced by interleukin-1beta, directly or indirectly through partial suppression of prostaglandin E2 synthesis. In addition, extracellular signal-regulated kinase, p38 MAPK, and c-Jun N-terminal kinase signals may co-operatively mediate interleukin-1beta-stimulated RANKL expression and its activity in those cells.

Psoriatic skin expresses the transcription factor Gli1: possible contribution of decreased neurofibromin expression

BACKGROUND

Psoriasis is a chronic inflammatory disorder of skin characterized by hyperproliferation of keratinocytes. Intracellular signalling pathways inducing the hyperproliferation of keratinocytes remain to be elucidated. An inhibitor of Hedgehog (Hh) signalling, cyclopamine, was recently reported to clear psoriatic skin lesions, suggesting involvement of the Hh signalling pathway in the hyperproliferation of lesional keratinocytes. We have previously observed activation of the Hh signalling pathway in Schwann cells of plexiform neurofibroma in neurofibromatosis type 1 (NF1), which results from functional loss of the NF1 encoding protein, neurofibromin. In psoriasis, deficiency of neurofibromin expression has been observed in lesional keratinocytes.

OBJECTIVES

To investigate whether the Hh signalling pathway would be activated in psoriasis and whether inhibition of neurofibromin expression would enhance the activation of the Hh signalling pathway.

METHODS

Activation of the Hh signalling pathway was examined by protein expression of one of the target genes, GLI1, coding for the transcription factor Gli1. Immunohistochemical studies were performed on seven psoriatic skin samples and seven control normal skin samples with a standard immunoperoxidase technique. mRNA expression of GLI1 was analysed by reverse transcriptase-polymerase chain reaction in HaCaT cells transfected with double-strand small interfering RNA for NF1.

RESULTS

Our results showed Gli1 expression in psoriatic skin but not in control normal skin. Inhibition of neurofibromin expression in HaCaT cells upregulated mRNA expression of GLI1.

CONCLUSIONS

Our findings indicate that the Hh signalling pathway is activated in psoriasis and that neurofibromin deficiency may upregulate the pathway.

A new simple therapeutic method for chronic subdural hematoma without irrigation and drainage

BACKGROUND

We developed a new simple therapeutic method for the treatment of chronic subdural hematoma (CSDH) without irrigation and drainage. This method is characterized by replacement of the hematoma with oxygen.

METHODS

Seventy patients (seventy-eight sides) with CSDH were treated with this method from May 1994 to October 2002. For the complete replacement of the hematoma with oxygen, subdural tapping site was changed from the thickest area of the hematoma to the parietal tuber. Irrigation and drainage were not used in all patients.

RESULTS

Neurological recovery after the treatment was satisfactory in all 70 patients. An average amount of replaced hematoma was 96.1 ml, ranging from 5 to 280 ml. An initial hematoma pressure ranged from 0 to 200 mm H2O (average: 92.1 mm H2O). During the follow up periods, clinical recurrence was noted in 7 patients (10%) and 7 sides (9.0%).

CONCLUSION

The replacement of the hematoma with oxygen via percutaneous subdural tapping without irrigation and drainage is useful and less invasive method for the treatment of CSDH.

gamma-Interferon enhances expression of CD14/MyD88 and subsequent responsiveness to lipopolysaccharide from Actinobacillus actinomycetemcomitans in human gingival fibroblasts

OBJECTIVES

CD14, toll-like receptor 4 (TLR4) and MyD88 have been shown to mediate responsiveness in host cells to lipopolysaccharide. We investigated here the regulatory effects of inflammatory cytokines on the expression of membrane CD14 (mCD14), TLR4 and MyD88, and on subsequent responsiveness to lipopolysaccharide from Actinobacillus actinomycetemcomitans in human gingival fibroblasts.

MATERIALS AND METHODS

Following treatment with either interleukin-1beta, tumor necrosis factor-alpha (TNF-alpha) or gamma-interferon (IFN-gamma), expression of mCD14/TLR4 and MyD88 was determined by flow cytometry and western blotting, respectively. After pretreatment with IFN-gamma, cells were pre-incubated with either anti-CD14 antibody MY4 or anti-TLR4 antibody HTA125 and subsequently treated with A. actinomycetemcomitans lipopolysaccharide. Then, phosphorylation of mitogen-activated protein (MAP) kinases and IkappaBalpha was examined by western blotting, and production of interleukin-6 and interleukin-8 was measured by their respective enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

IFN-gamma stimulated expression of mCD14, whereas -1beta and TNF-alpha did not. Expression of MyD88 but not TLR4 was also enhanced by IFN-gamma. The lipopolysaccharide activated MAP kinases, such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38, and IkappaBalpha and stimulated production of interleukin-6 and interleukin-8. The lipopolysaccharide-stimulated interleukin-6 and interleukin-8 production was markedly inhibited by MY4 or HTA125. Pretreatment with IFN-gamma augmented the following activation of MAP kinases and IkappaBalpha and production of interleukin-6 and interleukin-8 in response to the lipopolysaccharide.

CONCLUSIONS

These results suggest that the augmentation by IFN-gamma of the responsiveness to A. actinomycetemcomitans lipopolysaccharide, such as activation of MAP kinases and IkappaBalpha and terminal cytokine production in human gingival fibroblasts, may be partially mediated by up-regulation of CD14 and MyD88 expression.

Induced accumulation of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) in maize leaves

Accumulation of 2-(2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (HDMBOA-Glc) was induced in maize leaves by treatment with CuCl2, chitopentaose, penta-N-acetylchitopentaose, or jasmonic acid (JA). The accumulation of HDMBOA-Glc was accompanied by a decrease in level of 2-(2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (DIMBOA-Glc). When the leaf segments were treated with JA in the presence of [Me-2H3]L-methionine, the label was efficiently incorporated into HDMBOA-Glc, while no incorporation into DIMBOA-Glc or HMBOA-Glc was detected, suggesting the conversion of constitutive DIMBOA-Glc to HDMBOA-Glc by methylation at the 4-position. Levels of endogenous JA and its leucine conjugate transiently increased prior to the accumulation of HDMBOA-Glc in leaf segments treated with CuCl2 and chitopentaose. The lipoxygenase inhibitor ibuprofen suppressed the accumulation of HDMBOA-Glc induced by CuCl2 treatment, and the reduced accumulation of HDMBOA-Glc was recovered by addition of JA. These findings suggested that JA functions as a signal transducer in the induction of HDMBOA-Glc accumulation.

Acute epidural hematoma developing during twist-drill craniostomy: a complication of percutaneous subdural tapping for the treatment of chronic subdural hematoma

BACKGROUND

This case illustrates that although percutaneous subdural tapping for patients with chronic subdural hematoma (CSDH) is successful and minimally invasive, it can be complicated by acute epidural hematoma.

CASE PRESENTATION

A 62-year-old woman presented with headache two months after minor head trauma. Computed tomography (CT) scanning revealed CSDH with mixed density on the right side. Prior to percutaneous subdural tapping, twist-drill craniostomy was performed at the parietal tuber. When the drill-needle reached the dura mater, the patient began to complain of headache, which was followed by altered consciousness. CT scanning disclosed acute epidural hematoma abutting the CSDH; both hematomas were evacuated by emergency craniotomy. At surgery, no definite bleeding source was identified apart from oozing on the dura mater.

CONCLUSION

Hemorrhagic complications after percutaneous subdural tapping are rare. The formation of acute epidural hematoma during twist-drill craniostomy has not been reported in the literature. This complication can occur when the blunt tip of the drill-needle remains on the dura mater without penetrating into the subdural hematoma cavity.

Dissection of the middle cerebral artery caused by invasion of malignant glioma presenting as acute onset of hemiplegia

A 57-year-old, previously healthy man who developed acute onset of hemiplegia is presented. Neuro-imaging studies on admission suggested dissection of the middle cerebral artery producing infarction in the frontotemporal region. In contrast to his stable clinical course, serial neuro-imaging studies disclosed rapid growth of malignant glioma, which was confirmed at surgery. Microscopic examination of the surgical specimen demonstrated invasion of glioma cells into the arterial wall associated with intramural haematoma formation of the middle cerebral artery. This case is the first to document dissection of an intracranial artery caused by invasion of tumour cells.

Postoperative inflammatory reaction developing focal but severe brain edema. A possible complication of topical application of Biobond-soaked oxycellulose

A 66-year-old female underwent uneventful removal of parasagittal meningioma. At surgery, a piece of Biobond-soaked oxycellulose was applied to the lateral wall of the superior sagittal sinus for hemostasis. Her early postoperative course was complicated by focal but severe brain edema, which was adjacent to the hemostatic agent. Unlike foreign body granuloma previously reported, this complication was considered to be attributed to inflammatory reaction of Biobond, because of the early onset and fulminant edema despite of small volume of the mass lesion. Although there have been no previous reports of this complication, it should be kept in mind that intracranial application of Biobond may induce fulminant inflammatory reaction as seen in this patient.

Spontaneous intracranial hypotension associated with subdural hematoma: diagnostic usefulness of percutaneous subdural tapping and magnetic resonance imaging

A 55-year-old woman presented with headache which was characterized by aggravation in the upright position and relief in recumbency. Although intracranial hypotension syndrome was considered to be the most-likely possible entity, computed tomography (CT) scans demonstrated subdural fluid collections associated with findings reminiscent of transtentorial herniation. Because of these CT features, cerebrospinal fluid pressure measurement by a lumbar puncture was not performed. In stead, as an alternative method, she underwent percutaneous subdural tapping, which failed to obtain spontaneous drainage of liquid haematoma, indicating intracranial hypotension. In addition, gadolinium-enhanced magnetic resonance imaging study performed later supported the diagnosis of spontaneous intracranial hypotension. Thus, the usefulness and safety of percutaneous subdural tapping for the diagnosis of spontaneous intracranial hypotension is stressed.

Serial neuroimaging studies in Sotos syndrome (cerebral gigantism syndrome)

To elucidate the mechanism of excessive size of the head in Soto syndrome, serial neuroimaging features from birth were reviewed in two patients. Macrocephaly shortly after birth was attributed to increased volume of the cerebral parenchyma itself (megalencephalon). Subsequent excessive size of the head was related to retention of cerebrospinal fluid in the ventricles and the subarachnoid spaces. Thus, macrocephaly in Sotos syndrome reflects two different mechanisms. The value of serial evaluation of intracranial structures is emphasized.

Giant unruptured aneurysm of the vertebral artery presenting with rapidly progressing bulbar compression--case report

A 65-year-old male with a giant aneurysm of the vertebral artery, which had caused minimal neurological deficits for a few years, suffered rapid onset of respiratory disturbance followed by coma. Serial neuroimaging studies showed the thrombosed aneurysm continued to enlarge, resulting in increasing compression of the brainstem. Intraoperative observation and histological examination revealed that the aneurysm was composed of totally organized thrombus. Total extirpation of the giant aneurysm resulted in the patient regaining spontaneous respiration and clear consciousness, suggesting that growth of this aneurysm is due to increases in the size and number of the intrathrombotic capillary channels.

Infected subdural effusion associated with resolving subdural hematoma--case report

A 70-year-old male presented with rapid neurological deterioration and fever 3 months after suffering a closed head trauma. He underwent craniotomy for possible subdural empyema based on computed tomography and clinical findings. Dural incision revealed an outer membrane typical of chronic subdural hematoma which covered a clear, yellowish fluid containing Campylobacter fetus. Histological examination confirmed the capsule of the hematoma, with a necrotic focus infiltrated by neutrophils. Administration of intravenous imipenem and topical tobramycin and cefalothin achieved total resolution of his neurological deficits. Development of the infected subdural effusion was probably secondary to bacterial infection in the pre-existing chronic subdural hematoma in the resolving stage. The presence of the hematoma capsule always carries the risk of development of an infectious focus.

Isolated ophthalmological manifestations due to malfunction of a lumboperitoneal shunt: shortening of the spinal catheter in three pediatric patients

A long-term follow-up study was conducted in 28 pediatric patients treated with lumboperitoneal shunting. Shunt malfunction was observed in 3 patients (10.6%) who presented with isolated ophthalmological abnormalities 3, 5, and 11 years after surgery. The mechanism of this phenomenon is considered to be very slowly developing malfunction secondary to shortening of the spinal catheter associated with child's growth. The importance of periodic funduscopic examination in patients treated with lumboperitoneal shunting in infancy is stressed.

Hair-braiding closure for superficial wounds

A superficial scalp wound can be approximated by tying the hair on each edge of the wound, without shaving or using suture material. This technique is useful in selected patients with lacerated scalp wounds, and its technical details and indications are described.

Symptomatic subacute subdural hematoma associated with cerebral hemispheric swelling and ischemia

A 55-year-old man with traumatic acute subdural hematoma (SDH) was managed nonsurgically because of having isolated mild headache that resolved within a week. However, the patient developed an acute onset of amnestic aphasia 12 days post-trauma. Although the SDH itself did not increase in volume, remarkable swelling of the ipsilateral cerebral hemisphere was observed on CT scanning. Craniotomy was required since the main component of the SDH was solid and partially organized. Post-operative recovery from his speech disturbance was delayed, necessitating speech therapy for more than two months. Additionally, decreased cerebral blood flow on the affected side was observed even 3 months after injury. Symptomatic subacute SDH exclusively presenting as focal neurological deficits, though very rare,is worthwhile to be kept in mind as a pitfall in nonsurgical management of acute SDH.

Spontaneous regeneration of the foramen magnum after decompressive suboccipital craniectomy in Chiari malformation: case report

A 21-year-old woman, who had undergone foramen magnum decompression for her symptomatic Chiari malformation (Type 1) 7 years before, presented with recurrence of the symptoms. Neuroradiological examinations demonstrated regeneration of the foramen magnum that was caused by new bone formation, as confirmed at the second surgery. Neurological improvement was obtained after the removal of the regenerated foramen magnum. This observation, though rare, deserves to be kept in mind during the postoperative follow-up period in young patients with Chiari malformation.

A new class of DNA photolyases present in various organisms including aplacental mammals

DNA photolyase specifically repairs UV light-induced cyclobutane-type pyrimidine dimers in DNA through a light-dependent reaction mechanism. We have obtained photolyase genes from Drosophila melanogaster (fruit fly), Oryzias latipes (killifish) and the marsupial Potorous tridactylis (rat kangaroo), the first photolyase gene cloned from a mammalian species. The deduced amino acid sequences of these higher eukaryote genes show only limited homology with microbial photolyase genes. Together with the previously cloned Carassius auratus (goldfish) gene they form a separate group of photolyase genes. A new classification for photolyases comprising two distantly related groups is proposed. For functional analysis P.tridactylis photolyase was expressed and purified as glutathione S-transferase fusion protein from Escherichia coli cells. The biologically active protein contained FAD as light-absorbing cofactor, a property in common with the microbial class photolyases. Furthermore, we found in the archaebacterium Methanobacterium thermoautotrophicum a gene similar to the higher eukaryote photolyase genes, but we could not obtain evidence for the presence of a homologous gene in the human genome. Our results suggest a divergence of photolyase genes in early evolution.

Reversibility of cerebral ischaemia. Dynamic and xenon computed tomography study on ischaemic cerebrovascular disease

Flow studies using dynamic CT and xenon (Xe) CT were carried out in 25 patients with ischaemic stroke in the territory of the middle cerebral artery to define the clinical characteristics of cerebral ischaemia at a chronic stage. The parameter of peak height/mean transit time (PH/MTT) obtained from dynamic CT can provide an accurate index for blood circulation in the cerebral vascular bed. Xe CT measurements revealed various kinds of ischaemia around the infarction even in the chronic stages. In mild ischaemia of more than 30 ml/100 g/min, reduction of cerebral blood flow (CBF) was well correlated to the PH/MTT. However, in severe ischaemia between 20 and 30 ml/100 g/min, changes of CBF were no longer correlated with the PH/MTT. There were cases showing severe reduction of CBF but which showed sufficient blood circulation (moderate value of PH/MTT). Mild reductions of CBF in parallel with decreased blood supply were often found in the peri-infarct area of infarctions in the centrum semiovale. On the other hand, infarctions in the cortico-subcortical region showed severe ischaemia, in even where blood circulation was relatively well sustained.

Evolution of chronic subdural hematoma after burr-hole exploration for subdural effusion--case report

A 57-year-old male developed subdural effusion after head trauma, which remained asymptomatic and unchanged in volume during a follow-up period of 3 months. A typical chronic subdural hematoma (CSDH) developed 6 weeks after burr-hole exploration in spite of the absence of hematoma capsule or blood components in the effusion. The CSDH was successfully treated by irrigation and drainage. This case suggests that the presence of blood in subdural effusion may be the trigger for evolution of CSDH. We recommend that asymptomatic subdural effusion should be followed up without surgical intervention.

Clinical analysis of incidentally discovered unruptured aneurysms

BACKGROUND AND PURPOSE

We analyzed the risk factors for rupture of an intracranial aneurysm based on a retrospective angiographic study of ruptured and unruptured aneurysms.

METHODS

The 44 cases of asymptomatic aneurysms were selected from 1612 patients whose lesions had been discovered fortuitously by angiography (2.7%) during the period from 1980 to 1989. All these patients were free from any sign of intracranial aneurysm. The variations in age, sex, and location of the aneurysms were analyzed compared with 638 ruptured aneurysms that had been treated in our institute during the same period. The size, shape, and arterial geometry of the unruptured aneurysms were examined angiographically.

RESULTS

Unruptured aneurysm was discovered fortuitously in 44 (2.7%) of 1612 patients, with greater incidence in women aged older than 60 years. Unruptured aneurysms were less likely to occur in the anterior communicating artery (12.8%) and the middle cerebral artery (6.4%). However, they were frequently found in the internal carotid artery, with an incidence of 10.6% in cavernous portion of the internal carotid artery, 19.1% in the internal carotid-ophthalmic artery, 19.1% in the internal carotid-posterior communicating artery, and 12.8% in the internal carotid-anterior choroidal artery. Seven of the nine internal carotid-posterior communicating artery aneurysms showed a hypoplastic or aplastic posterior communicating artery. The mean diameter of the unruptured aneurysms was 4.8 mm, and 80% were smaller than 6 mm.

CONCLUSIONS

Intracranial aneurysms are formed not only at the bifurcation of an artery but also at its branching and bending points. However, an aneurysm located at the bifurcation, such as the anterior communicating artery and the middle cerebral artery, bleeds easily in contrast with lateral aneurysms such as those found at the branching and bending points on the internal carotid artery.

Arteriovenous malformation presenting as acute subdural haematoma

A case of acute subdural haematoma caused by ruptured arteriovenous malformation is reported. At surgery, there was no association with intracerebral haematoma or definite subarachnoid haemorrhage. The mechanism of acute subdural haematoma in the present case was considered to be rupture of an arteriolized bridging vein drained by arteriovenous malformation.

Okadaic acid, a protein phosphatase inhibitor, induces sister-chromatid exchanges depending on the presence of bromodeoxyuridine

Okadaic acid (OA), a potent tumor promoter and an inhibitor of protein phosphatase 1 and 2A, induced sister-chromatid exchanges (SCEs) in human lymphoblastoid cells and Chinese hamster ovary cells at low concentrations of 2-10 nM, when the cells were grown for two cell cycles in the presence of OA and bromodeoxyuridine (BrdUrd). Prolonged treatment with OA prior to addition of BrdUrd did not induce SCEs, indicating an essential role of BrdUrd. A similar important role of BrdUrd in SCE induction has been reported in the cases of benzamide (BA) (Natarajan et al., 1981) and camptothecin (CPT) (Zhao et al., 1992), which are inhibitors of poly(ADP-ribose)polymerase and DNA topoisomerase I (topo I), respectively. Unlike many DNA-damaging agents, they are required to be present during S phase along with BrdUrd in the medium and/or in the parental DNA as BrdUMP. Thus OA, like BA and CPT, is a new type of SCE inducer. Exposing cells to a combined treatment with OA, BA and CPT, a significantly higher level of SCEs was induced than that expected if the numbers of SCE caused by these three inhibitors were additive, while no such synergistic increase was seen in every combination of two agents. Since both phosphorylation and poly(ADP-ribosyl)ation have been known to modify topo I activity, the results suggest a common involvement of topo I for SCE formation by OA, BA and CPT. In addition to SCE induction, OA resulted in an increase of mitotic cells which were characterized by a marked chromosome condensation. OA also induced chromosome fragmentation/pulverization in human lymphoblastoid cells and fragmented nuclei in Chinese hamster cells.

Vertebral artery aneurysm at the level of the cervicomedullary junction--case report

A 39-year-old male presented with a ruptured vertebral artery aneurysm at the level of the cervicomedullary junction. Neuroradiological imaging demonstrated the aneurysm but not the anatomical relationships. Surgery in the chronic stage revealed that the aneurysm arose from the lowest part of the intradural vertebral artery. No vertebral artery proximal to the aneurysmal neck was identified in the intradural space. Clipping was difficult through the intradural approach. Acute treatment of such aneurysms requires control of the extradural vertebral artery with temporary clipping.

Identification of cellular defect in UVS1, a UV-sensitive Chinese hamster ovary mutant cell line

UVS1 is an intermediately UV-sensitive Chinese hamster ovary mutant originally isolated by its hypersensitivity to an anticancer drug, 1-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-3-(2-chloroethyl)-3-nitrosour ea hydrochloride. By cell fusion analysis, UVS1 complemented the UV sensitivity of the mouse lymphoma cell line US31 from the eighth complementation group of UV-sensitive rodent cell lines. By enzyme-linked immunosorbent assay we found that within 3 h after UV irradiation both pyrimidine dimers and (6-4)photoproducts in UVS1 were not removed from chromosomal DNA in UVS1 at all. Twenty-four h after UV irradiation the removal rate of (6-4)photoproducts was intermediate between CHO9, the parental cell line, and 43-3B, a UV-hypersensitive Chinese hamster ovary mutant of the complementation group 1, whereas the pyrimidine dimers in UVS1 were removed less efficiently as 43-3B. Alkaline elution assay showed that the incising activity to damaged DNA after UV irradiation of UVS1 was as low as that of 43-3B. The number of 1-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-3-(2-chloroethyl)-3-nitrosour ea hydrochloride-induced DNA interstrand cross-links of UVS1 was almost equal to that of 43-3B and about 1.5 times more than that of CHO9, suggesting that the gene products defective in UVS1 and 43-3B are essential for the excision repair of DNA damages produced by 1-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-3-(2-chloroethyl)-3-nitrosour ea hydrochloride.

A possible involvement of DNA topoisomerase I in "caffeine effect" after ultraviolet irradiation

Caffeine has been known to enhance lethal and chromosome damaging effects of chemical and physical mutagens. In spite of numerous investigations, the mechanism is not fully elucidated. In this paper, we describe that 1) post-treatment with camptothecin (CPT), a specific inhibitor of DNA topoisomerase (topo) I, enhances SCE-induction by ultraviolet light (UV), as post-UV caffeine treatment does, 2) the lethal effect of UV is also enhanced but to a lesser degree than by post-UV caffeine treatment, and 3) caffeine, like CPT, inhibits calf thymus topo I activity, as determined by relaxation of pBR322 supercoiled DNA. These results suggest that the mechanism(s) of lethal and SCE enhancement involves the ability of caffeine to inhibit topo I.

DNA repair pathways in mammalian cells analyzed by isolation of ACNU-sensitive Chinese hamster ovary cells

1-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-3-(2-chloroethyl)-3- nitrosourea hydrochloride (ACNU) causes chloroethylation of DNA strand followed by cross linking through an ethylene bridge. We recently isolated two ACNU sensitive mutants from mutagenized Chinese hamster ovary cells, and found them to be new drug sensitive recessive mutants (Hata et al. 1991). The O6-methyl guanine DNA methyl transferase (MT) activities of these cells were undetectable as the parental cell line, indicating that the sensitivity of the mutant cell lines to ACNU was not due to the decreased cellular level of this enzyme. By complementation analysis with the 7 established UV-sensitive CHO cell lines, one of the mutants, UVS1, turned out to complement their UV-sensitivity and, therefore, build a new complementation group among all the CHO cell lines ever reported. The other mutant, CNU1 showed hypersensitivity only to chlorethylating agents (ACNU, CCNU) and exhibited a slightly reduced unscheduled DNA synthesis (UDS) induced by UV. It is, therefore, suggestive that this mutant is defective in a specific step of DNA repair systems, which is important for the processing of DNA damages produced by ACNU. Only cell lines from the complementation group 1 and 4 out of 7 established complementation groups of UV-sensitive CHO mutants were more sensitive to ACNU than UVS1 and CNU1, indicating some steps of excision repair pathways as well as specific repair system play important roles in repairing ACNU-induced DNA damages.

Camptothecin-induced sister-chromatid exchange dependent on the presence of bromodeoxyuridine and the phase of the cell cycle

Camptothecin (CPT), a DNA topoisomerase I inhibitor, dose-dependently induced sister-chromatid exchanges (SCEs) in human lymphoblastoid cells NL3 when added with bromodeoxyuridine (BrdUrd) for 2 cell cycles. CPT given prior to the addition of BrdUrd scarcely induced SCEs. When cells with BrdUrd present for 2 cell cycles were treated with CPT in the first cell cycle, the SCE induction was evident, though its frequency was considerably lower than in cells treated in the second cell cycle, indicating that BrdUrd is essential for SCE induction by CPT. The replacement of BrdUrd with thymidine in the second cell cycle gave the same results in SCE induction and its removal without replacement resulted in a reduced but still clear induction by CPT treatment in the second cell cycle. These results indicate that BrdUrd, not only incorporated into DNA but also in the culture medium, plays an essential role in SCE induction by CPT. CPT treatment in the G1 phase of the second cell cycle also induced SCEs, as did treatment in the S phase. In phytohemagglutinin-stimulated peripheral lymphocytes, CPT given in the G1 phase of the second cell cycle, but not of the first one, also induced SCEs though to a lesser degree. These findings suggest that CPT is capable of inducing DNA lesions during the G1 phase when chromosomes contain BrdUrd-substituted DNA. The lesions are presumably formed in connection with transcription, which requires topoisomerase I activity, and are believed to be long-lived enough to induce SCEs in the following S phase.

Patterning in hydra cell aggregates without the sorting of cells from different axial origins

Aggregates of Hydra cells were studied to find out how the primary centers that form new heads are generated in a system of cells in which the original pattern has been destroyed. Since cells that originate near the heads (apical cells) temporarily maintain a high level of head activation potential during aggregate formation and may contribute to pattern formation, their distribution in the aggregates was investigated. The mutual distances between labeled epithelial cells were followed by vitally staining apical cells with DAPI. The distribution was random during early regeneration stages (3, 6, 24 hr). These results show that epithelial cells originating from apical regions do not sort. That is, dynamic cell movement to generate rudiments of new heads is not necessary for head formation in aggregates. A possible explanation of the mechanism is discussed.

Mitochondrial DNA repair by photolyase

Photolyase genes of Saccharomyces cerevisiae and Escherichia coli were expressed in S. cerevisiae and photoreactivation in nuclei and mitochondria of the host cells was analyzed by determination of survival and petit rates. Yeast photolyase was able to repair mitochondrial DNA effectively, whereas E. coli photolyase could reduce only a small fraction of the petit rate produced by UV irradiation. Analysis using fusion between yeast photolyase and E. coli lacZ genes as well as a chimeric gene between yeast and E. coli photolyase genes suggests the importance of the protruding amino terminal region of the yeast photolyase for its transport into mitochondria. A significant similarity between the protruding amino termini of yeast photolyase and yeast uracil-DNA-glycosylase suggests a common functional importance of the terminal sequences for both DNA repair enzymes.

Cloning and functional characterization of a eucaryotic DNA photolyase gene from Neurospora crassa

We cloned a genomic fragment of a photolyase gene from Neurospora crassa by polymerase chain reaction using synthesized oligonucleotide primers designed from the most conserved amino acid sequences among photolyases of various organisms. Using the cloned fragment as a hybridization probe we isolated a genomic fragment and cDNA clones encoding the complete photolyase gene of this organism. The amino acid sequence of the photolyase deduced from the determined nucleotide sequence indicates a protein consisting of 615 amino acid residues (Mr 69,971), which is most similar to that of Saccharomyces cerevisiae. Like yeast photolyase it contains a protruding amino terminus which is missing in photolyases of bacterial origin. Comparison of amino acids sequences among six photolyases suggests that the Neurospora crassa photolyase is more similar to photolyases of pterin type than those of deazaflavin type.

Role of cysteine residues in the activity of rat glutathione transferase P (7-7): elucidation by oligonucleotide site-directed mutagenesis

To clarify the role(s) of thiol (sulfhydryl) groups of cysteine (Cys) residues in the activity of the rat glutathione transferase P (7-7) form (GST-P), a cDNA clone, pGP5, containing the entire coding sequence of GST-P (Y. Sugioka et al., (1985) Nucleic Acids Res. 13, 6044-6057) was inserted into the expression vector pKK233-2 and the recombinant GST-P (rGST-P) expressed in E. coli JM109. All four Cys residues in rGST-P were independently substituted with alanine (Ala) by site-directed mutagenesis, the resultant mutants as well as the rGST-P being identical to GST-P purified from liver preneoplastic nodules with regard to molecular weight and immunochemical staining. Since all mutants proved as enzymatically active towards 1-chloro-2,4-dinitrobenzene as liver GST-P, it was indicated that none of the four Cys residues is essential for GST-P activity. However, the mutant with Ala at the 47th position from the N-terminus (Ala47) became resistant to irreversible inactivation by 0.1 mM N-ethylmaleimide (NEM), whereas the other three mutants remained as sensitive as the nonmutant type (rGST-P). Ala47 was also resistant to inactivation by the physiological disulfides, cystamine or cystine, which cause mixed disulfide and/or intra- or inter-subunit disulfide bond formation. These results suggest that the 47-Cys residue of GST-P may be located near the glutathione binding site, and modulation of this residue by thiol/disulfide exchange may play an important role in regulation of activity.

Acute subdural haematoma successfully treated by percutaneous subdural tapping in an elderly patient

An elderly patient suffering acute subdural haematoma associated with cerebral contusion was treated by percutaneous subdural tapping while preparing for craniotomy. Most of the subdural haematoma, though of high density on computed tomography scanning, proved to be semiliquid. Drainage of the haematoma yielded resolution of the mass effect, and was followed by a rapid improvement of consciousness. This observation suggests the significance of trial subdural tapping for the treatment of acute traumatic subdural haematoma prior to craniotomy.

Unique characteristics of superoxide dismutase of a strictly anaerobic archaebacterium Methanobacterium thermoautotrophicum

The superoxide dismutase (SOD) gene of Methanobacterium thermoautotrophicum (Takao, M., Oikawa, A., and Yasui, A. (1990) Arch. Biochem. Biophys. 283, 210-216), a strictly anaerobic archaebacterium, was expressed in Escherichia coli. The gene product accounted for more than 30% of the host's soluble protein. The purified protein was an active iron-containing tetrameric SOD with specific activity similar to known manganese-containing SODs (MnSODs) of aerobic archaebacteria. Although M. thermoautotrophicum SOD is an iron-containing SOD (FeSOD), it resembles MnSODs in amino acid sequence as judged by criteria distinguishing FeSODs from MnSODs. Moreover, M. thermoautotrophicum SOD is resistant to azide and hydrogen peroxide as MnSODs are, suggesting that its evolution is distinct from known eubacterial FeSODs.

Intracranial arteriovenous fistula manifesting as progressive neurological deterioration in an infant: case report

This 1-year-old male infant had been diagnosed with cerebral degenerative disease because he developed psychomotor regression, and brain atrophy was demonstrated on computed tomography. He underwent magnetic resonance imaging, which suggested a cerebrovascular malformation. Cerebral angiography disclosed an arteriovenous fistula, fed by an anterior cerebral artery and directly draining into a cortical vein. The occlusion of the feeding artery was followed by a satisfactory recovery. The mechanism of the neurological symptoms in this patient is thought to be caused by a steal phenomenon and compression of the brain stem by venous engorgement in the posterior fossa.

Isolation of two chloroethylnitrosourea-sensitive Chinese hamster cell lines

1-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-3-(2-chloroethyl)-3- nitrosourea hydrochloride (ACNU), a cancer chemotherapeutic bifunctional alkylating agent, causes chloroethylation of DNA and subsequent DNA strand cross-linking through an ethylene bridge. We isolated and characterized two ACNU-sensitive mutants from mutagenized Chinese hamster ovary cells and found them to be new drug-sensitive recessive Chinese hamster mutants. Both mutants were sensitive to various monofunctional alkylating agents in a way similar to that of the parental cell lines CHO9. One mutant (UVS1) was cross-sensitive to UV and complemented the UV sensitivity of all Chinese hamster cell lines of 7 established complementation groups. Since UV-induced unscheduled DNA synthesis was very low, a new locus related to excision repair is thought to be defective in this cell line. Another ACNU-sensitive mutant, CNU1, was slightly more sensitive to UV than the parent cell line. CNU1 was cross-sensitive to 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea and slightly more sensitive to mitomycin C. No increased accumulation of ACNU and a low level of UV-induced unscheduled DNA synthesis in this cell as compared with the parental cell line suggest that there is abnormality in a repair response of this mutant cell to some types of DNA cross-links.

Characterization of a superoxide dismutase gene from the archaebacterium Methanobacterium thermoautotrophicum

A gene encoding superoxide dismutase (SOD) was cloned from the archaebacterium Methanobacterium thermoautotrophicum, the first example from an anaerobic bacterium. The deduced amino acid sequence showed overall similarity to sequences of known Mn- and Fe-SODs from aerobic organisms. Judging from a detailed sequence comparison, the cloned SOD gene is classified as Mn-SOD. By comparison of Mn-SOD sequences among various species it was suggested that archaebacterial superoxide dismutase is a direct descendant of a primordial enzyme. Between a putative promoter and the start codon there is an inverted repeat sequence which is also found in the counterpart of Halobacterium halobium.

Increased UV sensitivity of Escherichia coli cells after introduction of foreign photolyase genes

High-expression plasmids for photolyase (phr) genes from the bacteria Escherichia coli, Anacystis nidulans, Streptomyces griseus and Halobacterium halobium and the yeast Saccharomyces cerevisiae were constructed and introduced into E. coli phr recA cells. As previously reported, al introduced phr genes provided the host cells with photoreactivation-repair activity and the introduced E. coli phr gene rendered the host cells more UV-resistant in the dark. E. coli cells harboring foreign phr genes, however, were found to be more sensitive to UV light in the dark than cells containing the vector plasmid only. These differences in UV sensitivity in the dark disappeared when the host cells had an additional mutation, uvrA, suggesting that the foreign photolyases inhibited the E. coli excision-repair system.

Hypoxanthine enhances hydroxyurea-induced sister-chromatid exchanges in Chinese hamster ovary cells

Treatment with 1 mM hydroxyurea (HU) for 12 h induced sister-chromatid exchange (SCE) in CHO-K1 cells. The induced SCE frequency was always higher in cells grown in Ham's F12 medium than in those grown in RPMI 1640 medium. It was shown that hypoxanthine (Hyp), a component of Ham's F12, was to a great extent responsible for producing a higher level of HU-induced SCEs: HU-induced SCEs were synergistically enhanced when Hyp was added to RPMI 1640 medium supplemented with dialyzed fetal bovine serum at a concentration of 30 microM, which is the concentration in Ham's F12 medium. The radioactivity of [14C]Hyp was readily incorporated into DNA in either the presence or the absence of HU. The greater part was in the forms of dGMP and dAMP. It was not clear whether Hyp was incorporated in the form of dIMP or not. Deoxyguanosine (dGuo), but not deoxyadenosine (dAdo) reversed both the incorporation of radioactivity into DNA and the SCE-enhancing effect of Hyp. Our results indicate that incorporation of Hyp into the dNTP pools and into the DNA, together with perturbation of dGuo metabolism under abnormal conditions during and after HU treatment, is involved in the enhancement by Hyp of HU-induced SCEs.

Expression of an Anacystis nidulans photolyase gene in Escherichia coli; functional complementation and modified action spectrum of photoreactivation

The Anacystis nidulans photolyase gene inserted in an expression vector plasmid was introduced into Escherichia coli cells and the production of Anacystis photolyase protein was confirmed by reaction with antibodies raised against photolyase purified from A. nidulans cells. The Anacystis photolyase functioned in photoreactivation repair defective E. coli cells. The E. coli transformants exhibited an action spectrum with a maximum around 380 nm similar to that of E. coli photolyase in contrast with the action spectrum of A. nidulans cells which has a maximum at 437 nm. These results indicate that the Anacystis photolyase produced in E. coli cells has enzymatic activity in spite of the apparent lack of its intrinsic 8-hydroxy-5-deazaflavin cofactor.

Tandem arrangement of photolyase and superoxide dismutase genes in Halobacterium halobium

A DNA fragment containing the photolyase gene was cloned from Halobacterium halobium. The deduced amino acid sequence is highly similar to those of four known photolyases from eubacteria and a eucaryote. The cloned gene expressed in Escherichia coli increased the survival of UV-irradiated host cells by photoreactivation. These results indicate that photolyases of eucaryotes, eubacteria, and archaebacteria are derived from a common origin. In this cloned DNA fragment, two additional open reading frames (ORFs), ORF 151 and ORF 200, were found in the 5' and 3' adjacent flanking regions of the photolyase gene. ORF 200 shows unequivocal amino acid sequence homology to all known manganese and iron superoxide dismutases. Northern (RNA) hybridization analysis of H. halobium RNA revealed the existence of three transcripts, one of which covered all three ORFs, indicating that photolyase and superoxide dismutase are partly cotranscribed in this bacterium.