Large Photothermal Effect in Sub-40 nm h-BN Nanostructures Patterned Via High-Resolution Ion Beam.

The controlled nanoscale patterning of 2D materials is a promising approach for engineering the optoelectronic, thermal, and mechanical properties of these materials to achieve novel functionalities and devices. Herein, high-resolution patterning of hexagonal boron nitride (h-BN) is demonstrated via both helium and neon ion beams and an optimal dosage range for both ions that serve as a baseline for insulating 2D materials is identified. Through this nanofabrication approach, a grating with a 35 nm pitch, individual structure sizes down to 20 nm, and additional nanostructures created by patterning crystal step edges are demonstrated. Raman spectroscopy is used to study the defects induced by the ion beam patterning and is correlated to scanning probe microscopy. Photothermal and scanning near-field optical microscopy measure the resulting near-field absorption and scattering of the nanostructures. These measurements reveal a large photothermal expansion of nanostructured h-BN that is dependent on the height to width aspect ratio of the nanostructures. This effect is attributed to the large anisotropy of the thermal expansion coefficients of h-BN and the nanostructuring implemented. The photothermal expansion should be present in other van der Waals materials with large anisotropy and can lead to applications such as nanomechanical switches driven by light.

Experimental measurement of quality factor enhancement using slow light modes in one dimensional photonic crystal.

We experimentally investigate the effects of slow light modes within a one dimensional photonic crystal resonator. We show that the slow light mode leads to significant increase in the quality factor of the resonator. We provide a theoretical analysis explaining our experimental results. We also include the effect of disorder to simulate the fabrication imperfection. Further results regarding the properties of the one dimensional photonic crystal are discussed.

Phylogenetic relationships of HTLV-I/STLV-I in the world.

In an effort to delineate the origin and evolution of HTLV-I/STLV-I, we have been conducting phylogenetic analyses on LTR sequences of this virus group. HTLV-I isolates newly analyzed in the present study were from Iran, South Africa, Cameroon, Sakhalin and Brazil where little is known concerning the genetic features of HTLV-I. In addition, STLV-I isolates were obtained from non-human primates in Africa and Asia including an isolate from orangutans in Indonesia. Proviral LTR sequences were amplified by nested PCR, and then sequenced. Phylogenetic trees were constructed by the neighbor joining method. The results obtained are: 1) African STLV-I isolates formed one large cluster together with the Central African group of HTLV-I in the tree; 2) Asian STLV-I isolates including that of an orangutan in Indonesia were highly divergent from African STLV-I and the Cosmopolitan group of HTLV-I, but not so closely related to each other and to the Melanesian group of HTLV-I; 3) An HTLV-I isolate of Cameroon Pygmy was related to African STLV-I isolates, but distinct from the Central African group of HTLV-I; 4) The majority of HTLV-I isolates belonged to subgroup A which is the most widespread subgroup of the Cosmopolitan group of HTLV-I, while some Brazilian isolates from descendants of Japanese immigrants belonged to subgroup B which mainly consists of HTLV-I isolates from Japan. 5) In the phylogenetic tree, several HTLV-I isolates of subgroup A from the same areas appear to form monophyletic clusters such as a subcluster of Brazilian and Colombian isolates and that of Iranian isolates.

Angioimmunoblastic lymphadenopathy with disseminated human herpesvirus 6 infection in a patient with acute myeloblastic leukemia.

A 47-year-old man with acute myeloblastic leukemia (AML) developed angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) 4 months after induction chemotherapy for AML. During a leukopenic period, the patient suffered from pericarditis with massive pericardial effusion in which human herpesvirus 6 (HHV-6) DNA was detected. Although complete remission of AML was achieved, fever persisted and atypical skin rash followed by generalized lymphadenopathy along with polyclonal hypergammaglobulinemia appeared. A diagnosis of AILD was made on a biopsy specimen of the inguinal lymph node. The patient died of fulminant hepatitis and the autopsy showed lymphomatous infiltrates involving the liver, bone marrow, lungs, spleen, kidneys and heart. HHV-6 DNA sequences were identified in the biopsy specimen of the lymph node and in the involved organ tissues. HHV-6 in this patient was variant B. It is known that HHV-6 can be reactivated in immunocompromised patients and causes severe complications. This unusual clinical course suggests that the immunosuppression associated with AML and the additional iatrogenic immunosuppression following cytopenia-inducing chemotherapy predisposed the patient to reactivated HHV-6 infection. The sequential detection of this virus before and after manifestation of AILD may support the evidence that HHV-6 infection could directly or indirectly trigger AILD. This is the first time that such a sequence of events has been reported to our knowledge. The possibility of HHV-6 infection should be considered when unexplained fever and generalized lymphadenopathy are seen in patients with leukemia, and administration of antiviral agents should be considered for the diagnostic evaluation.

Serological survey of HIV-1, HIV-2 and human T-cell leukemia virus type 1 for suspected AIDS cases in Ghana.

OBJECTIVE: To determine seroprevalence among suspected AIDS patients in Ghana in relation to clinical manifestations. MATERIALS AND METHODS: Blood samples and medical records were collected from 290 Ghanaian patients with suspected AIDS in 1990 and 1992. Seroprevalence of HIV-1, HIV-2 and human T-cell leukemia virus (HTLV-1) were investigated by the particle agglutination method, indirect immunofluorescence assay, the monoepitope enzyme-linked immunosorbent assay and Western blot. RESULTS: The specimens were classified into five serologic categories: 78 were HIV-1-positive (26.9%), 25 were HIV-2-positive (8.6%), 17 dual-positive (5.9%), 16 indeterminate (5.5%) and 154 seronegative (53.1%). No significant difference was found between the clinical symptoms of patients with HIV-1 and HIV-2 infection. Of the patients, 14 (4.8%) were HTLV-1-seropositive, of whom 11 were also HIV-positive, indicating a significant correlation between the two groups of viral infections (P < 0.01). However, there was no evidence of an increase in severity of symptoms in cases of dual infection with HTLV-1 and HIV. CONCLUSIONS: HIV-1 infection is now dominant in Ghana in contrast to our previous survey in 1986 which showed the dominance of HIV-2. The change in seroprevalence suggests that an HIV-1 epidemic has been developing in recent years in this country, where HIV-2 was originally endemic. A relatively high prevalence of dual-reactive specimens implies the existence of highly cross-reactive strains of HIV or frequent coinfection with HIV-1 and HIV-2 in the region. The large number of seronegative patients with clinically diagnosed AIDS raises the question of the inadequacy of AIDS definitions based on clinical manifestations only.

Chimeric viruses between SIVmac and various HIV-1 isolates have biological properties that are similar to those of the parental HIV-1.

OBJECTIVE: To examine the biological properties of HIV-1/SIVmac chimeric viruses from HIV-1 isolates that have different replication rates, cell tropisms and cytopathicities. DESIGN AND METHODS: Four chimeric viruses with gag, pol, vif, vpx, nef and long terminal repeats of SIVmax and vpr, tat, rev, vpu and env of various HIV-1 isolates were constructed and compared in vitro. Cynomolgus monkeys were inoculated with two chimeras that were replicative in monkey peripheral blood mononuclear cells (PBMC). RESULTS: The type-specific neutralization of the chimeras by monoclonal antibodies 0.5 beta and mu 5.5, which recognize V3 of HIV-1IIIB and HIV-1MN respectively, was observed to be similar to those of the parental viruses, HIV-1NL432, HIV-1HAN2 and HIV-1SF13. The chimeras constructed from HIV-1SF2 and HIV-1SF13, which were isolates from the same individual but from different disease stages, reflected their parental properties, that is, the isolate from the later stage was rapid-high replicating, was more cytopathic and had a wider host range. Chimeras constructed from HIV-1HAN2' HIV-1SF13 and HIV-1NL432 were infectious to macaque monkeys, although the monkeys infected with the chimera from HIV-1SF13 showed lower virus loads and shorter viremic periods than those infected with the others. CONCLUSIONS: Chimeras have in vitro properties that are similar to those of their parental HIV-1 isolates, but their growth in macaque PBMC was dependent on which HIV-1 isolate was used. Evaluation of a vaccine by challenging with viruses possessing different antigenicities has become possible in macaque monkeys using newly constructed chimeras.

Development of novel simian immunodeficiency virus vectors carrying a dual gene expression system.

The development of highly efficient and safe gene transfer methods suitable for clinical use is required for human gene therapies. We have developed a novel lentiviral vector system, based on the nonpathogenic simian immunodeficiency virus from African green monkeys (SIVagm), that carries a unique dual gene expression system. This system utilizes the lentivirus Rev responsive element (RRE). Self-inactivating vectors were also developed by deleting a U3 region in the 3' long terminal repeat (3' LTR) of the virus. When pseudotyped with a vesicular stomatitis virus envelope glycoprotein G (VSV-G), the SIVagm-based vectors could transduce both growth-arrested human cells and terminally differentiated neuronal cell lines. Using these vectors, two reporter genes could be expressed simultaneously at equal levels, and expression levels of both genes could be altered by modifying the length of the RRE sequence. These SIVagm-based vectors might offer safety advantages over other lentivirus-based vectors. Furthermore, the novel dual gene expression system described here could increase the usefulness and value of both viral and nonviral vectors in gene therapy.

An experimental application of gene therapy for human retinoblastoma.

PURPOSE: The purpose was to determine the potential of gene therapy for retinoblastoma using transfer of the herpes simplex virus thymidine kinase (HSV-TK) gene into retinoblastoma cells (Y79 cell line). METHODS: A retrovirus-packaging cell line PA317 was electroporated with a retroviral vector plasmid bearing HSV-TK and neomycin-resistance genes to produce a PA317-TK cell line releasing a replication-defective vector bearing both genes. Y79 was transduced by exposure to transmissible virus-containing medium from PA317-TK, and new clones of Y79 containing the HSV-TK gene (Y79-TK) were established. Sensitivity to ganciclovir (GCV) and acyclovir (ACV) was investigated in Y79 and Y79-TK and the effect of HSV-TK-positive cells on negative cells ("bystander effect") was determined in vitro. The effect of antitumorigenesis in a nude mouse system was also investigated. RESULTS: There were no differences in the growth pattern or the morphology between Y79 and Y79-TK. Y79-TK was more sensitive to GCV and ACV than was Y79. The cytotoxicity of Y79-TK was dose dependent. An obvious "bystander effect" was present with the addition of GCV. In vivo studies confirmed the ability of GCV to kill Y79-TK. CONCLUSIONS: In this study a model is proposed for the introduction of a drug-sensitivity gene into Y79 and the possibility is raised of treating retinoblastoma with gene therapy. The results suggest that the transfer of the HSV-TK gene into Y79 followed by the administration of GCV could serve as a model for gene therapy for retinoblastoma.

Expression of exogenous p59fyn modulates signaling in an immature B cell line, WEHI-231.

The WEHI-231 B lymphoma line is representative of immature B cells, which undergo growth arrest/apoptosis following cross-linking of surface immunoglobulin M (sIgM). In B cells, sIgM engagement has been shown to induce immediate (within seconds) activation of src family protein tyrosine kinases (PTKs) such as p53lyn/56lyn, p55blk, p56lck and p59fyn which are associated with B cell antigen receptor (BCR) complex. However, p59fyn expression is very low in both normal immature B cells and apoptosis-prone B cell lines, including WEHI-231. Such a finding prompted us to investigate the effects of ectopic expression of p59fyn in growth regulation of WEHI-231 cells. We have obtained WEHI-231 transfectants expressing the exogenous p59fyn by retroviral mediated gene transfer method. The transfectants demonstrated increased [Ca2+]i level in both the non-stimulated condition and sIgM cross-linking. The expression of ectopic p59fyn also increased the sensitivity of the transfectants to growth arrest signal by sIgM cross-linking. The results suggest that p59fyn can modulate signal transduction and growth regulation when expressed in the immature B cell line.

HIV type 1 genetic variability in the northern part of Cameroon.

In 1995, 53 blood samples from Muslim patients with AIDS, or who were thought to have AIDS, were collected in the main hospitals of Adamaoua Province, in the northern part of Cameroon. The variable env C2V3 region of HIV-1 was amplified by nested PCR and phylogenetically analyzed. The results indicated that of 15 amplified samples, 1 belonged to HIV-1 group O, 1 to HIV-1 subtype D, 1 to subtype G, 2 to subtype H, and 10 to subtype A. Furthermore, the northern Cameroonian subtype A could be divided into at least two subclusters as shown by the env tree as well as by two remarkably conserved hexameric amino acid sequences in the apex of V3 (GPGQAF in one subcluster and GPGQTF in the other). This distinction suggests that the HIV-1 subtype A circulating in northern Cameroon evolved from two main sources. More recently, three HIV-1 strains from Nigeria (IBNG) and Djibouti (DJ263 and DJ264), previously reported on the basis of their env C2V3 sequences as subtype A, were found to have a similar A/G mosaic structure alongside their full-length sequence and were tentatively designated as members of a new subtype called "IBNG." Interestingly, within the northern Cameroonian subtype A described, the isolates of the second subcluster clustered distinctly with these A/G mosaic strains, strongly suggesting that they may be members of the IBNG subtype.

Mutational analysis of two zinc finger motifs in HIV type 1 nucleocapsid proteins: effects on proteolytic processing of Gag precursors and particle formation.

To clarify the physiological function of two zinc finger motifs in the nucleocapsid (NC) domain of the Gag protein of human immunodeficiency virus type 1 (HIV-1), we changed cysteine to serine in either of the two motifs or both by site-directed mutagenesis. Viral infectivity was lost by any of the mutations, but their effects appeared differently in the respective mutants. Northern blot analysis showed that the first finger mutant was far less efficient (approximately 10% of the wild type) in genomic RNA encapsidation and that the dual mutant of both fingers completely failed to encapsidate the RNA. In contrast, the second finger mutant retained its ability for RNA encapsidation with an efficiency similar to that of the wild type. Immunoblot analysis of the lysates of CD4-positive M8166 cells transfected with the mutant proviral DNAs showed that the processing of Gag precursors was delayed in two mutant viruses having alterations in the first finger sequence, whereas the processing of the second finger mutant appeared to be normal. On the other hand, immunoblot analysis of the virus particles showed that the second finger mutant particles contained some proteins that were thought to be degradation products of p24CA. Electron microscopic observation showed that all particles of these mutant viruses were morphologically alike except that they had a slightly larger diameter than that of the wild type. These results indicate that these finger motifs of HIV-1 NC protein do not function equivalently. Namely, the first finger is primarily responsible for RNA encapsidation and the second is required for stabilization of virus particles.

Sequential analysis of apoptosis induction in peripheral blood mononuclear cells and lymph nodes in the early phase of pathogenic and nonpathogenic SIVmac infection.

To investigate the role of apoptosis in the early phase of HIV infection, we used macaques infected with simian immunodeficiency virus strain mac (SIVmac) as a primate model and examined sequentially the characteristics of apoptosis of lymphocytes in peripheral blood mononuclear cells (PBMCs) and lymph nodes in the early phase of SIVmac infection. Five macaques infected with a pathogenic strain of SIV, SIVmac239, were analyzed during the first 4 weeks after infection. Peripheral CD4+ and CD8+ cells transiently decreased at 1 week postinfection. The percentage of apoptotic cells in cultured PBMCs increased from about 2 weeks postinfection. The number of apoptotic cells in lymph node sections was higher on days 13 and 28 postinfection than before infection and on day 5 postinfection. Fas antigen expression on peripheral lymphocytes was upregulated from day 8 postinfection. These results indicate that apoptosis is induced about 2 weeks after SIVmac239 infection, following the upregulation of Fas antigen expression on lymphocytes. Since apoptosis was induced about 1 week after the decrease in peripheral CD4+ and CD8+ cell counts, it appears that the apoptosis induction does not play an important role in the transient lymphopenia in the early phase of SIVmac infection. In macaques infected with a nonpathogenic derivative of SIVmac239, SIVmac delta nef, apoptosis of lymphocytes was induced as it was in SIVmac239-infected macaques, but to a lesser degree, suggesting a correlation between the extent of apoptosis induction in lymphocytes in the early phase of SIVmac infection and the pathogenicity of SIVmac.

Genetic subtypes of HIV type 1 in Republic of Congo.

To assess the molecular epidemiology of HIV-1 in Republic of Congo (Congo), we investigated 29 HIV-1s obtained from 82 Congolese AIDS and ARC patients in 1996 and 1997. Part of the env region including the V3 loop was phylogenetically analyzed. The genotypes observed were varied: of 29 specimens, 12 (41 %) were subtype A, 1 (3%) was subtype D, 6 (21%) were subtype G, 6 (21%) were subtype H, 2 (7%) were subtype J, and 2 (7%) could not be classified as any known subtypes (U, unclassified). The heterogeneous profile of HIV-1 infection was different from the profiles of neighboring Central African countries. These data show that subtypes G and H as well as subtype A were circulating with high prevalence. The fact that new genetic subtypes (J and U) are circulating indicates a need for a greater surveillance for these subtypes both in Congo as well as in other parts of the world.

S-100 protein-positive dendritic cells detected in hepatocellular-carcinoma in relation to tumor progression and prognosis.

The presence of S-100 protein positive dendritic cells (S-100(+)DC) in primary hepatocellular carcinoma (HCC) were immunohistochemically investigated in relation to clinicopathological factors. The patients who showed a marked infiltration of S-100(+)DC survived longer especially in the group of non-curative resection (P<0.05). In addition, the density numbers of S-100(+)DC related well with the rate of growth of each tumor nodule calculated by ultrasonography (r=0.575, P<0.01). These results indicate that, S-100(+) DC, acting as antigen presenting cells, may play an important role in the host's immune reaction against HCC and are a useful marker for tumor growth and prognosis in HCC.

Epithelioid sarcoma producing granulocyte colony-stimulating factor.

An epithelioid sarcoma of the perineum of a 60-year-old man with widespread metastases produced leukocytosis, myeloid hyperplasia of the bone marrow, and splenomegaly. High titers of granulocyte colony-stimulating factor (G-CSF) were found in the patient's serum and primary culture medium of the tumor tissue. The tumor tissue extract contained m-RNA for G-CSF in large quantities, proving that the tumor was the source of this cytokine.

Entrapment and inhibition of human immunodeficiency virus proteinase by alpha 2-macroglobulin and structural changes in the inhibitor.

The inhibitory effect of alpha 2-macroglobulin (alpha 2M), a major plasma proteinase inhibitor, on human immunodeficiency virus (HIV) proteinase was investigated. The activity of HIV proteinase toward the Moloney murine sarcoma virus-derived gag protein (a high-molecular-mass substrate) was found to be inhibited by alpha 2M at pH 5.5-7.4. On the other hand, the activity toward the B chain of oxidized insulin (a low-molecular-mass substrate) was scarcely inhibited. The complex of alpha 2M and HIV proteinase was isolated by gel filtration and the enzyme was shown to be significantly protected by the complex formation from autoinactivation under nonreducing conditions. The stoichiometry of the complex formation was found to be 2:1 (enzyme: alpha 2M, mol/mol). These results demonstrate the entrapment and concomitant inhibition of HIV proteinase by alpha 2M.

Myolipoma of the round ligament: report of a case with a review of the English literature.

Tumours consisting of a mixture of mature adipose and smooth muscle tissues, including those designated lipoleiomyomas, fibrolipoleiomyomas and myolipomas, are exceedingly rare, but most often occur in the uterine corpus. We describe here a case of such a tumour arising in the right round ligament of a 44-year-old woman. The tumour, which measured approximately 20x15x10 cm, was well encapsulated and did not involve the intrapelvic organs. Intricate mixtures of adult adipose tissue and bland smooth muscle exhibited no cellular atypia or nuclear mitotic figures, and there was little vascular proliferation. We diagnosed the lesion as a myolipoma of soft tissue with dual differentiation, and have found only 13 cases of this tumour including our own in the English literature. The present tumour is the first reported in the round ligament. Although this tumour is rare, its recognition is important for the avoidance of erroneous diagnoses.

Multilocular thymic cysts associated with thymoma. A case report.

The association of multilocular thymic cysts (MTC) with thymoma is exceedingly rare, and the pathogenesis of this combination is controversial. We describe the case of a 42-year-old man with an anterior mediastinal mass found to contain MTC and thymoma. A multilocular cystic mass, measuring 13 x 6.5 x 2 cm, was found in the right lobe of the thymus, and contained a 4.7 x 2 cm thymoma in its center. Microscopic thymomas, lipomatously involuted remaining thymic tissue, and lymphoid follicles with germinal centers were found in the walls of MTC as well as in the left thymic lobe. Non-specific chronic inflammation was also present in the walls. In addition, microcysts, which were only found at the periphery of the thymoma and covered with epithelium, might have been formed secondarily by dilatation of the perivascular spaces and of Hassall's corpuscles. These findings suggest that a chronic inflammatory process was responsible for the early formation and enlargement of this patient's MTC, and that while the cavities of the MTC expanded to various degrees, the thymoma, which originated from one of the microscopic thymomas in the walls of MTC, increased in size, and grew to involve the remaining thymic tissue.

Immunohistochemical study of epithelioid hemangioendothelioma in the leg: a case report.

Epithelioid hemangioendothelioma is a relatively rare lesion. Although its histogenesis has been well described, its immunohistochemical characteristics remain controversial. A case of epithelioid hemangioendothelioma of the soft tissue of the right leg in a 67-year-old Chinese woman is reported. Histologic findings of intracytoplasmic lumina in the tumor cells and positive immunostaining for vimentin, factor VIII-related antigen. CD34 and Ulex europaeus agglutinin 1 (UEA-1) were obtained, demonstrating differentiation of the tumor cells to endothelial cells, although staining for antibodies to cytokeratins AE1/AE3 and CAM5.2 was weak. CD34 as well as Factor VIII-related antigen is a useful marker of endothelial differentiation in this tumor. A review of the literature is also presented.

Rapid and progressive CD4+ decline in a monkey infected with an SIV+HIV-1 chimeric virus.

We previously constructed a simian immunodeficiency virus+human immunodeficiency virus type 1 (HIV-1) chimeric virus, NM-3rN to generate a pathogenic HIV-1 in macaque monkeys. During the in vivo passage of this virus in several monkeys, a viral strain, R43-56 was obtained which acquired a better replication ability in vivo. MM121, one of the three monkeys inoculated with the R43-56, showed weight loss, diarrhea and a rapid and continuous decrease in CD4+ lymphocytes at the moribund stage. An autopsy revealed generalized lymphadenopathy, dehydration, and ileocecal intussusception. In situ hybridization showed that the virus infection was in systemic lymphoid organs. We are presently monitoring the survivors to obtain candidates for a more virulent virus. R43-56 may be a better challenge virus and useful tool for human acquired immunodeficiency syndrome research.