Optical implementation of carry generation for a multiwavelength full adder

We propose the implementation of an optical multiwavelength full adder. Several optical wavelengths are used to encode the bits of the binary numbers to be added so that the broad spectral bandwidth of optical systems can be utilized. We demonstrate the carry generation for the proposed optical multiwavelength full adder, using a novel scheme of four-wave mixing in photorefractive crystals.

Kinetics of a cellular response to interleukin 6

The stimulation of the production of haptoglobin from the human hepatoma HepG2 was used as a model to examine the kinetics of a cellular response to interleukin 6 (IL-6). It was demonstrated that IL-6 upregulated the production of haptoglobin in a time-dependent manner: using a sensitive radioimmunoassay for haptoglobin, increases were already detectable 2 hr after IL-6 treatment began. The haptoglobin level continued to rise in a linear fashion to at least 16 hr. The stimulation of haptoglobin by IL-6 was abolished in the presence of 5 micrograms/ml actinomycin D and was thus likely pretranslational. It was further demonstrated that the upregulation of haptoglobin continued well after the removal of IL-6 from the system. An 8-hr "pulse" of IL-6 gave rise to haptoglobin secretion which was above control levels for the following 4 days. The effects of IL-6 in vivo can therefore be predicted to be long-lived despite its own short half-life, especially since the products of IL-6 stimulation, e.g., immunoglobulin and acute-phase proteins, are themselves long-lived in the circulation.

Tissue reactions to titanium implants containing bovine bone morphogenetic protein: a scanning electron microscopic investigation

Cylindric titanium implants treated with bovine bone morphogenetic protein (bBMP) (Group I) and with bovine serum albumin (BSA) (Group II) were implanted in the edentulous mandibles of 15 adult dogs. They were examined 1, 2, 4, 8, and 12 weeks after insertion of the implants by scanning electron microscopy (SEM). In all specimens from Group I, active bone formation had occurred between the implant and host bone, with a well-adapted fit between the implant and the newly formed bone 4 weeks after implantation. The surrounding bone was of normal structure by week 8. However, 3 months after implantation, fibrous tissue was consistently seen surrounding parts of the implants in Group II. The results of this study suggest that the implants treated with bBMP are capable of forming new bone of normal structure at a faster rate than BSA controls and that this new bone is closely adapted to the implant surface.

Photoinduced birefringence rotation in germanosilicate glass optical fiber

Experimental results are reported for the permanent photoinduced rotation of the principal axes of the birefringence in a circular-core single-mode optical fiber on exposure of the fiber to powerful argon-laser radiation at 488 nm. The linearly polarized laser beam was launched into the fiber along one of the principal axes of the initial birefringence in the fiber. After several exposures totaling 4 h, a rotation of as much as 57 degrees was observed in the orientations of the principal axes in addition to the photoinduced birefringence.

The neural retina maintains integrins in the apical membrane of the RPE early in development

PURPOSE

The retinal pigment epithelium (RPE) lines the interface between the neural retina and the choroid. Early in chicken development, the beta 1 family of integrins resides in the apical (facing the neural retina) and basolateral (facing the choroid) membranes of RPE. Later in development, integrins reside only in the basolateral membranes, which is more typical of simple transporting epithelia. The authors examined whether the distribution of integrins is regulated by the neural retina.

METHODS

Individual integrins were examined by studying the individual alpha-subunits that form heterodimers with the beta 1 subunit. The expression and distribution of these subunits were determined by immunoblotting and immunocytochemistry.

RESULTS

Subunits alpha 3 and alpha 6 exemplified contrasting behaviors. Early and late in development, alpha 3 was found only in the basal membranes. As was beta 1, the distribution of alpha 6 was nonpolarized early in development but was basal later in development. The effect of the immature neural retina was determined by reconstituting the RPE:neural retinal interface in explant culture. Absent the neural retina, alpha 6 and beta 1 were removed from the apical membrane. When present, the immature neural retina maintained both subunits in the apical membrane. The neural retina was effective only if the outer (primordial photoreceptor) surface of the retina apposed the RPE.

CONCLUSIONS

These data suggest that matrix or intercellular interactions determine the distribution of individual integrins. Further, the changes in integrin distribution during development reflect the maturation of the primordial interphotoreceptor matrix or photoreceptor cell layer.

Modified-signed-digit arithmetic for multi-input digital optical computing

We propose and demonstrate a modified-signed-digit (MSP) arithmetic to achieve multi-input digital optical computing. Our approach utilizes hybrid addition-subtraction transformation (or weight operation) rules among multiple inputs. This results in operation speeds that exceed those of two-input MSD arithmetic for multi-input computing. Optical'implementation of the proposed multi-input MSD arithmetic by utilizing spatial data encoding and an optical fan-out element is also presented and experimentally demonstrated.

Histocytochemistry of glycoconjugates in nasal inverted papilloma

In order to investigate the changes in cellular distribution of the glycocalyces in nasal inverted papilloma, formalin-fixed, paraffin-embedded biopsy specimens of inverted papilloma were analyzed by the avidin-biotin-peroxidase complex technique for the demonstration of peanut agglutinin (PNA) receptors, concanavalin A (Canavalia ensiformis agglutinin; ConA) receptors, carcinoembryonic antigen (CEA), and keratin, and compared with normal nasal mucosa, nasal polyps, and papillary adenocarcinoma. The inverted papillomas were positive for PNA and CEA, to the same degree as papillary adenocarcinoma. Their PNA binding was related to the degree of dysplasia. The ConA reaction was intermediate between that of normal mucosa and adenocarcinoma. The results suggest that the alteration of cellular glycoprotein structure in inverted papilloma is associated with its biologic characterization.

[Experimental study on delayed reinnervation of vocal cord adductors]

The adductor branch was anastomosed with the main branch of ansa cervicalis to reinnervate the vocal cord adductors in six dogs at the time of denervation and after varying intervals of chronic denervation. Some recovery of adduction was noted within ten-month interval. Laryngeal electromyography, tension tests and histologic studies of the adductor muscles were correlated with the recovery of adduction. Although adduction didn't recover after twelve-month interval, striations of the adductor muscles were normal, only slight fibrosis was observed.

A 9-year follow-up study of the immunogenicity and long-term efficacy of plasma-derived hepatitis B vaccine in high-risk Chinese neonates

The long-term immunogenicity of and protection provided by a plasma-derived hepatitis B vaccine was determined in a cohort of 98 susceptible Chinese neonates immunized in 1982-1983. Within 24 hours of birth, 89 infants received the first of three 30-micrograms doses of vaccine (at 0, 1, and 6 months) and were subsequently followed up by testing for serological markers of hepatitis B virus and by determining levels of alanine aminotransferase annually for 9 years. After the primary series of vaccine doses, 74 (83%) of 89 subjects developed antibody to hepatitis B surface antigen (anti-HBs). At the 9-year follow-up, 51% of vaccinees still had levels of antibody of > or = 10 mIU/mL, considered the protective level. Seven responders to vaccine (9.4% of 74 evaluable patients) developed antibody to hepatitis B core antigen, and in six of these responders, levels of anti-HBs increased transiently. None of the vaccinees developed chronic carriage of hepatitis B surface antigen or clinical hepatitis. Immunization of high-risk neonates with a plasma-derived hepatitis B vaccine can induce long-lasting protective immunity that can prevent or modify primary infection for at least 9 years. Booster doses are not necessary during this period.

Molecular cloning and characterization of dTAFII30 alpha and dTAFII30 beta: two small subunits of Drosophila TFIID

The multisubunit transcription factor TFIID is an essential component of the RNA polymerase II initiation apparatus. Recent studies suggest that TFIID subunits, or TAFs associated with the TATA-binding protein (TBP), play a critical role in modulating transcriptional activation by sequence-specific DNA-binding factors. Thus far, six of the largest TAFs associated with Drosophila TFIID have been cloned and partially characterized. Here, we report the molecular cloning, expression, and subunit interaction specificities of two small molecular mass TAFs. Both dTAFII30 alpha and dTAFII30 beta are associated with TFIID via interactions with other TAFs, including dTAFII250, dTAFII150, and dTAFII110. In addition, dTAFII30 alpha also contacts dTBP. The carboxy-terminal half of dTAFII110 was found to contact a short 67-amino-acid region of dTAFII30 alpha, which is predicted to form two potential alpha-helices, one of which is amphipathic. Interestingly, dTAFII30 alpha also appears to multimerize through its carboxy-terminal region. Although neither dTAFII30 alpha nor dTAFII30 beta have been found to interact with specific activators thus far, it is intriguing that both bind other TAFs such as dTAFII110 and dTAFII150, which are the targets of activation domains. Our studies suggest that both of the small subunits of TFIID play a role in the assembly of the complex and may contribute to the stability of multiple TAF-TAF interactions.

Parallelizing I/O intensive applications for a workstation cluster

An I/O intensive application, parallel full text retrieval based on a signature file method, is studied. The text retrieval system is implemented on a cluster of DEC5000 workstations connected by Ethernet. Experiments are performed to evaluate the benefit and cost for running such an application in a workstation cluster. Results show that substantial improvement in speed can be obtained through parallelism in disk accesses, despite the high communication and synchronization overhead that is incurred. Several factors that affect the performance of a parallel I/O application in this type of computing environment are discussed. The advantages of a workstation cluster are its large combined I/O buffer capacity, and possible concurrent accesses to disks local to each workstation. Our study demonstrates that these advantages, when exploited properly, can lead to effective performance improvement without the need for additional hardware.

Ozonolysis products of membrane fatty acids activate eicosanoid metabolism in human airway epithelial cells

When inhaled, ozone reacts at the airway luminal surface with unsaturated fatty acids contained in the extracellular fluid and plasma membrane to form an aldehyde and hydroxyhydroperoxide. The resulting hydroxyhydroperoxide degrades in aqueous systems to yield a second aldehyde and hydrogen peroxide (H2O2). Previously, we demonstrated that ozone can augment eicosanoid metabolism in bovine airway epithelial cells. To examine structure-activity relationships of ozone-fatty acid degradation products on eicosanoid metabolism in human airway epithelial cells, 3-, 6-, and 9-carbon saturated aldehydes and hydroxyhydroperoxides were synthesized and purified. Eicosanoid metabolism was evaluated by determination of total 3H-activity release from confluent cells previously incubated with [3H]arachidonic acid and by identification of specific metabolites with high performance liquid chromatography and radioimmunoassay. The major metabolites detected were prostaglandin E2, prostaglandin F2 alpha, and 15-hydroxyeicosatetraenoic acid. The 9-carbon aldehyde, nonanal, in contrast to 3- or 6-carbon aldehydes, stimulated release at concentrations > or = 100 microM, suggesting that the stimulatory effect increases with increasing chain length. When tested under identical conditions, the 3-, 6-, and 9-carbon hydroxyhydroperoxides were more potent than the corresponding aldehydes. Again, a greater effect was noted when the chain length was increased. One possible explanation for the increased potency of the hydroxyhydroperoxides over the aldehydes could be due to degradation of the hydroxyhydroperoxide into H2O2 and aldehyde. We consider this an unlikely explanation because responses varied with chain length (although each hydroxyhydroperoxide would produce an equivalent amount of H2O2) and because exposure to H2O2 alone or H2O2 plus hexanal produced a response dissimilar to 1-hydroxy-1-hexanehydroperoxide.(ABSTRACT TRUNCATED AT 250 WORDS)

Polarization- and space-encoded parallel optical fuzzy logic processor

A novel polarization- and space-encoded parallel optical fuzzy logic processor is proposed and demonstrated by use of optical fan-out elements and polarization multiplexing. Sixteen fuzzy logic operations between two inputs are achieved with a simple data-encoding scheme. Our system exhibits a high operation speed, a high signalto- noise ratio, a large information throughput, and the capacity to operate on two channels of polarization states independently.

Polarization-encoded optical logic operations in photorefractive media

We propose and demonstrate optical logic operations using polarization encoding and wave mixing in photorefractive crystals. In our approach two orthogonal polarization states of light beams are used to represent respective logic values of 1 and 0. All 16 two-input logic operations can be easily achieved by use of the recording and readout of photoinduced volume gratings in photorefractive crystals. An optical full adder is also proposed and demonstrated.

[The effects of phenytoin and carbamazepine on the cognitive function of epileptic patients]

We made a comparative study of the cognitive function of 60 epileptic patients before and after the use of phenytoin (DPH) and carbamazepine (CBZ). Five types of neuropsychological tests were adopted. Although both DPH and CBZ affected cognitive function, the degrees of their effects were not the same. DPH affected cognitive function in a broad field, including concentration, remembrance, psychological motor speed and mental processing, whereas CBZ had only slight effect on perception and motor speed. It is stressed that cognitive function disorder caused by antiepileptic drugs should be early detected by synchronous examinations of the level of antiepileptic drugs and the neuropsychological functions.

[Dot immunobinding assay for detection of three types of rheumatoid factor and its clinical significance]

We set up a dot immunobinding assay method for determination of IgM-, IgG- and IgA-rheumatoid factor (RF) and report here the results in 86 patients with rheumatoid arthritis (RA). It was found that the positive rates of IgM-, IgG- and IgA-RF were 59.7%, 54.7% and 17.4% respectively. The total positive rate was 72.8%. The positive rate using the Latex method was only 43.0%. Our results reveal that dot immunobinding assay for RF is more sensitive than the Latex method. Furthermore, there was a profound correlation of IgG-RF with active stage and the frequency of extra-artivular manifestations in RA patients.

The synapse-specific phosphoprotein F1-20 is identical to the clathrin assembly protein AP-3

F1-20 and AP-3 are independently described, synapse-associated, developmentally regulated phosphoproteins with similar apparent molecular masses on SDS-polyacrylamide gel electrophoresis (PAGE). F1-20 was cloned and characterized because of its synapse specificity. AP-3 was purified and studied biochemically because of its function as a clathrin assembly protein. Here we present evidence that establishes the identity of F1-20 and AP-3. Monoclonal antibodies against F1-20 and AP-3 both specifically recognize a single protein from mouse brain with an apparent molecular mass of 190 kDa on SDS-PAGE. These monoclonal antibodies also specifically recognize the cloned F1-20 protein expressed in Escherichia coli. The anti-F1-20 monoclonal antibody (mAb) stains a bovine protein with an apparent molecular mass on SDS-PAGE of 190 kDa that copurifies with brain clathrin-coated vesicles (CCVs) and that can be extracted from the brain CCVs under conditions that extract AP-3. The anti-F1-20 and anti-AP-3 mAbs specifically recognize the same spot on a two-dimensional gel run on a bovine brain clathrin-coated vesicle extract. AP-3 purified from bovine brain CCVs is recognized by both the anti-F1-20 and anti-AP-3 mAbs. Purified preparations of bovine AP-3 and bacterially expressed mouse F1-20 give identical patterns of protease digestion with bromelain and subtilisin. Sequence analyses reveal that F1-20 has an essentially neutral 30-kDa NH2-terminal domain with an amino acid composition typical of a globular structure and an acidic COOH-terminal domain rich in proline, serine, threonine, and alanine. This is consistent with proteolysis experiments that suggested that AP-3 could be divided into a 30-kDa globular uncharged clathrin-binding domain and an acidic, anomalously migrating domain.

[The changes in free radical and prostaglandin metabolism in newborn infants with asphyxia]

Blood plasma thromboxane-B2 (TXB2) and 6-keto-PGF1 alpha levels were determined by radioimmunoassay technique during the first six to sixteen hours of life in 16 newborn infants with severe asphyxia, 18 newborn infants with mild asphyxia and 27 normal term neonates. Plasma lipid peroxidation (LPO) content was measured by TBA-colour-contrast method in 15 infants with severe asphyxia, 17 infants with mild asphyxia and 24 healthy term newborn infants. The results showed that blood plasma LPO, TXB2 and 6-keto-PGF1 alpha levels in infants suffering from severe asphyxia were higher than those in infants with mild asphyxia and normal infants (P < 0.01), but no significant difference was noted between the mild asphyxia group and normal control group (P > 0.01). These suggest that production of free radicals is increased and prostaglandin metabolism is triggered in the infants with severe asphyxia, that cerebral ischemia and hypoxia caused by asphyxia contributes to the augmented production of prostaglandins and free radicals, and that accumulation of free radicals and prostaglandin enhances brain damage and the metabolism of arachidonic acid appears to be an important source of the free radicals in infants with intrauterine asphyxia.

Explant culture of rabbit tracheobronchial epithelium: structure and prostaglandin metabolism

This study examines the potential usefulness of explant culture of rabbit tracheal epithelium as a model for the study of epithelial function under normal and potentially pathologic conditions. Accordingly, we assessed the structure and prostaglandin E2 (PGE2) release of tracheal epithelial explants obtained from adult pathogen-free rabbits. Epithelial cells attached to their native connective tissue substratum were maintained in culture for 5 days in serum-free medium, under bipolar conditions (air-liquid interface) on a permeable membrane (pore size, 0.2 mm), and nourished from the basolateral surface. At 5 days in culture, scanning and transmission electron microscopy and light microscopy demonstrated a pseudostratified, ciliated columnar epithelium with prominent folds and mucus secretion identical in appearance to the mucosa before culture. On the day of dissection (day 0) and after 4 days in culture (day 4), explants released PGE2 into the medium spontaneously. However, day 4 explants produced 3- to 4-fold greater amounts of PGE2 than day 0 explants. Moreover, day 4 explants demonstrated increased PGE2 release in response to bradykinin, a receptor-dependent agonist, and ionomycin, a calcium ionophore, while day 0 explants did not. Primary tracheal epithelial cell cultures grown to confluence (day 9) on a collagen substrate demonstrated PGE2 responses to bradykinin and ionomycin that qualitatively resembled those of day 4 explants. We conclude that rabbit tracheal explants cultured in vitro under the above conditions maintain cellular differentiation, in situ three-dimensional organization, and PGE2 synthetic pathways over several days in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Monolithic self-Q-switched Cr,Nd:YAG laser

We report the operation of a diode-pumped monolithic self-Q-switched Cr,Nd:YAG laser in which the codoped ions create saturable absorption for Nd(3+) laser emission at 1064 nm. With a 70-microm beam diameter in the gain medium, the Q-switched pulse has a duration of 3.5 ns and a peak power of 2 kW. The output is linearly polarized with an extinction ratio of 600:1. The pulse-to-pulse intensity fluctuation is less than the instrument resolution of 0.25%. A 5-mm-long KTP crystal butted against the monolithic cavity produces 2-ns-long pulses at 532nm with a peak power-conversion efficiency of 30%.

Microsurgical replantation of the avulsed scalp: report of six cases

This article reports the successful microsurgical replantation of six scalps avulsed for over 3 to 11 hr, after trauma and before repair, including five total and one partial avulsion. The authors believe that one key to successful replantation is effective vessel anastomoses. In the reported series, three scalps were reconstructed with two superficial temporal vessels and in five cases, with a 1:1 ratio between arteries and veins. The partially avulsed scalp was replanted successfully with only one artery and one vein. The management of postoperative complications is discussed.

Financing health care in rural China: preliminary report of a nationwide study

One unforeseen consequence of the change from collective to household production in rural China has been that the financial basis of the rural health services has been eroded. The majority of peasants now pay for health care on a fee-for-service basis. A major initiative aimed at the establishment of prepayment schemes for funding rural health services is underway. A nationwide survey which compared health utilization and expenditure under different financing mechanisms was carried out in 1988. This paper presents the preliminary findings of that study. There is evidence that hospital charges were a barrier to inpatient care for those not covered by an insurance scheme. The data were less clearcut with regard to access to outpatient care. There is a need for further study which focuses on poor households and those living in remote villages. The study found that drug charges are an important source of revenue for the rural health services. The impact of this on prescription practices is an area which requires additional research. The cost of rural health services was relatively low. It is feasible to finance them almost entirely out of local resources in the more developed regions. The situation in the poorer provinces is more complicated. In spite of the fact that average health expenditure was almost 5% of household income in 1988, there was evidence of lack of access. This suggests that it may be more difficult to develop prepayment schemes to cover the full range of rural health services in the less developed regions.

Successful replication of parvovirus B19 in the human megakaryocytic leukemia cell line MB-02

The pathogenic human parvovirus B19 has been shown to undergo productive replication in the erythroid lineage in primary normal human hematopoietic progenitor cells. However, none of the established erythroleukemia cell lines has allowed B19 virus replication in vitro. The remarkable erythroid tissue tropism of B19 virus was evaluated with a human megakaryocytic leukemia cell line, MB-02, which is dependent on the growth factor granulocyte-macrophage colony-stimulating factor but can be induced to undergo erythroid differentiation following treatment with erythropoietin (Epo). Whereas these cells did not support B19 virus DNA replication in the presence of granulocyte-macrophage colony-stimulating factor alone, active viral DNA replication was observed if the cells were exposed to Epo for 5 to 10 days prior to B19 virus infection, as detected by the presence of the characteristic B19 virus DNA replicative intermediates on Southern blots. No replication occurred if the cells were treated with Epo for 3 days or less. In addition, complete expression of the B19 virus genome also occurred in Epo-treated MB-02 cells, as detected by Northern blot analysis. B19 progeny virions were released into culture supernatants that were biologically active in secondary infection of normal human bone marrow cells. The availability of the only homogeneous permanent cell line in which induction of erythroid differentiation leads to a permissive state for B19 virus replication in vitro promises to yield new and useful information on the molecular basis of the erythroid tissue tropism as well as parvovirus B19-induced pathogenesis.

A micromolar pool of antigenically distinct precursors is required to initiate cooperative assembly of hepatitis B virus capsids in Xenopus oocytes

Assembly of hepatitis B virus capsid-like (core) particles occurs efficiently in a variety of heterologous systems via aggregation of approximately 180 molecules of a single 21.5-kDa core protein (p21.5), resulting in an icosahedral capsid structure with T = 3 symmetry. Recent studies on the assembly of hepatitis B virus core particles in Xenopus oocytes suggested that dimers of p21.5 represent the major building block from which capsids are generated. Here we determined the concentration dependence of this assembly process. By injecting serially diluted synthetic p21.5 mRNA into Xenopus oocytes, we expressed different levels of intracellular p21.5 and monitored the production of p21.5 dimers and capsids by radiolabeling and immunoprecipitation, by radioimmunoassay, or by quantitative enzyme-linked immunosorbent assay analysis. The data revealed that (i) p21.5 dimers and capsids are antigenically distinct, (ii) capsid assembly is a highly cooperative and concentration-dependent process, and (iii) p21.5 must accumulate to a signature concentration of approximately 0.7 to 0.8 microM before capsid assembly initiates. This assembly process is strikingly similar to the assembly of RNA bacteriophage R17 as defined by in vitro studies.

Modified-signed-digit optical computing by using fan-out elements

We present a novel three-step modified-signed-digit optical computing system based on the discrete correlation of space-coded input matrices that are multiply imaged by using optical fan-out elements. The advantages of our method over other approaches include a larger throughput, more flexible operation, and an easier optical implementation.

Hepatitis B virus capsid particles are assembled from core-protein dimer precursors

Our studies on the assembly of hepatitis B virus capsids or core particles in Xenopus oocytes have demonstrated that unassembled p21.5 core proteins ("free p21.5") provide a pool of low-molecular-mass precursors for core-particle assembly. Here we have characterized this material. Free p21.5 sedimented through gradients of 3-25% sucrose (wt/vol) as a single protein species of approximately 40 kDa, corresponding to a p21.5 dimer. On nonreducing SDS/polyacrylamide gels, free p21.5 migrated as disulfide-linked p21.5 dimeric species of 35 and 37 kDa. Truncated core proteins lacking most or all of the 36-amino acid protamine region at the p21.5 carboxyl terminus were also found to behave as disulfide-linked dimers with appropriately reduced molecular masses. Our experiments failed to reveal monomeric core proteins or stable intermediates between dimers and capsids along the assembly pathway. We conclude that hepatitis B virus core particles are most likely assembled by aggregating 90 (or possibly 180) disulfide-linked p21.5 dimers. We discuss similarities between the assembly of hepatitis B virus capsids and simple T = 3 plant virus and bacteriophage structures.

RNA- and DNA-binding activities in hepatitis B virus capsid protein: a model for their roles in viral replication

The hepatitis B virus capsid or core protein (p21.5) binds nucleic acid through a carboxy-terminal protamine region that contains nucleic acid-binding motifs organized into four repeats (I to IV). Using carboxy-terminally truncated proteins expressed in Escherichia coli, we detected both RNA- and DNA-binding activities within the repeats. RNA-binding and packaging activity, assessed by resolving purified E. coli capsids on agarose gels and disclosing their RNA content with ethidium bromide, required only the proximal repeat I (RRRDRGRS). Strikingly, a mutant in which four Arg residues replaced repeat I was competent to package RNA, demonstrating that Arg residues drive RNA binding. In contrast, probing immobilized core proteins with 32P-nucleic acid revealed an activity which (i) required more of the protamine region (repeats I and II), (ii) appeared to bind DNA better than RNA, and (iii) was apparently modulated by phosphorylation in p21.5 derived from Xenopus oocytes. Deletion analysis suggested that this activity may depend on an SPXX-type DNA-binding motif in repeat II. Similar motifs found in repeats III and IV may also function to bind DNA. On the basis of these observations, together with a reinterpretation of recent studies showing that capsid protein mutants cause defects in viral genome replication, we propose a model suggesting that hepadnavirus capsid proteins participate directly in the intracapsid reverse transcription of RNA into DNA. In this model, repeat I binds RNA whereas the distal repeats are progressively recruited to bind elongating DNA strands. The latter motifs may be required for replication to be energetically feasible.

Cys residues of the hepatitis B virus capsid protein are not essential for the assembly of viral core particles but can influence their stability

In the spherical capsid of hepatitis B virus (HBV), intermolecular disulfide bonds cross-link the approximately 180 p21.5 capsid protein subunits into a stable lattice. In this study, we used mutant capsid proteins to investigate the role that disulfide bonds and the four p21.5 Cys residues (positions 48, 61, 107, and 185) play in capsid assembly and/or stabilization. p21.5 Cys residues were either replaced by Ala or removed (Cys-185) by carboxyl-terminal truncation, creating Cys-minus mutants which were expressed in Xenopus oocytes via microinjected synthetic mRNAs. Fractionation of radiolabeled oocyte extracts on 10 to 60% sucrose gradients revealed that Cys-minus core proteins resolved into the nonparticulate and capsid forms seen for wild-type p21.5. On 5 to 30% sucrose gradients, nonparticulate Cys-minus core proteins sedimented as dimers of approximately 40 kDa. We conclude that Cys residues and disulfides are not required for the assembly of either HBV capsids or the dimers that provide the precursors for capsid assembly. Since assembly presumably demands an appropriate p21.5 tertiary structure, it is unlikely that Cys residues are required for proper p21.5 folding. However, Cys residues stabilize isolated p21.5 structures, as evidenced by the marked reduction in stability of Cys-minus dimers and capsids (i) in nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis and (ii) upon protease digestion. We discuss these results in the context of the HBV life cycle and the role of Cys residues in other proteins.

Hemophilic blood cyst--a case report

We report a case of hemophilic blood cyst in a patient with human immunodeficiency virus (HIV) infection. The pathogenesis, diagnosis and treatment are discussed, and neither inflammatory changes nor pathological cells were seen in the numerous histological sections obtained surgically.

Parvovirus B19 replication in human umbilical cord blood cells

The human parvovirus B19 is now known to be one of the causative agents of nonimmune hydrops fetalis and spontaneous abortions in pregnant women. The presence of the viral proteins and antibodies in fetuses of B19-infected women suggests that the virus can cross the placental barrier. In order to gain an insight into the mechanism of intrauterine fetal infection and the virus-induced hydrops fetalis, we examined whether human umbilical cord blood cells were permissive for B19 replication. Cord blood cells were infected with B19 in vitro, and Southern blot analyses of low M(r) DNA isolated from these cells revealed the presence of the characteristic replicative intermediates of B19 DNA. In addition, B19 genome expression in cord blood cells was detected by Northern blot analysis. Quantitative DNA dot blot analysis of culture supernatants documented complete assembly and release of B19 progeny virions in these cells. The progeny virions were biologically active in secondary infections of normal human bone marrow cells. The human umbilical cord blood cells may be a useful alternative to bone marrow and fetal liver culture systems for further studies on B19 since the need for bone marrow donors is obviated and, unlike fetal tissues, there are no ethical questions associated with the experimental use of cord blood because it is normally discarded. These studies also suggest that the umbilical cord blood may be a site for active replication of parvovirus B19 in vivo and may thus provide a means for transmission of the virus during intrauterine fetal infections.

A technique to harvest viable tracheobronchial epithelial cells from living human donors

The ability to obtain airway epithelial cells from the lower respiratory tract in living human donors will facilitate study of the biologic properties of these cells. We report our experience harvesting tracheobronchial epithelial cells from living human donors by brushing the mucosal surface of the trachea and mainstem bronchi. Cells were obtained on 21 occasions from 18 healthy adult subjects under direct vision with a brush-tipped catheter during fiberoptic bronchoscopy. The average number of cells harvested per subject was 14 +/- 2 x 10(6), and cell viability determined by trypan blue exclusion averaged 36 +/- 4%. Of note, cell viability was significantly enhanced when lidocaine was confined to the nares. Lidocaine was also observed to diminish cell viability in vitro in a dose-dependent fashion. Morphologic and staining properties were used to classify harvested cells into the three major cell types present in the mucosa (i.e., ciliated, secretory, and basal cells). All three subtypes were obtained. The percentage of ciliated, secretory, and basal-like cells was 24 +/- 2%, 11 +/- 1%, 29 +/- 1%, respectively, while the remaining 36% were difficult to type. In one subject in whom brushing was performed on three occasions over a 7-wk period, the percentage of each of the three subtypes was similar across procedures. Harvested cells could be successfully placed in primary culture with a plating efficiency of 50 to 60% and could be subcultured for up to seven passages. Acutely dissociated cells could be used to study the beta-adrenergic receptor adenylyl cyclase system since they produced cAMP in response to isoproterenol.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of a novel synapse-specific protein. II. cDNA cloning and sequence analysis of the F1-20 protein

The F1-20 protein is a novel neuronal-specific, synapse-associated protein that is expressed nonuniformly in mouse brain. Expression of the F1-20 protein is developmentally regulated in a pattern coincident with active synaptogenesis and synaptic maturation. Here we report the cloning of the cDNA sequence for the F1-20 protein. We found two distinct isoforms of F1-20 cDNA that differed by the presence of 15 additional nucleotides, which does not interrupt the open reading frame. RNase protection analysis and PCR amplification of mouse brain RNA revealed that both isoforms are present in cellular RNA. It is likely that the two F1-20 mRNA isoforms are derived from RNA splicing events utilizing alternative 3' acceptor sites. Analysis of the deduced amino acid sequence for the complete open reading frame revealed that the predominant F1-20 mRNA encodes an 896 amino acid polypeptide with a molecular weight of 91,319 Da. The deduced amino acid sequence does not contain a signal sequence, or any extensive hydrophobic regions. The deduced amino acid sequence does contain a number of consensus sequences for protein kinases. Searches of the protein and nucleic acid sequence data bases revealed that the F1-20 protein has not been previously characterized at the primary structure level, although a weak similarity was found between rabbit calpastatin and the C-terminal portion of the F1-20 protein. We then determined biochemically that the F1-20 protein is a substrate for Ca(2+)-dependent proteolysis, which is specifically inhibited by calpain inhibitors in vitro. This indicates that the F1-20 protein is a substrate for neuronal calpain. We observed that treatment of a synaptosomal lysate with alkaline phosphatase led to an increase in the electrophoretic mobility of the F1-20 protein, as well as to an increase in the sharpness of the electrophoretic band. This indicates that the F1-20 protein is phosphorylated in vivo.

Characterization of a novel synapse-specific protein. I. Developmental expression and cellular localization of the F1-20 protein and mRNA

A molecular description of the nerve terminal will be required to understand synaptic function fully. The goals of this study were to contribute toward such a description by characterizing a novel synapse-specific protein. A monoclonal antibody library was screened for antibodies to synaptic proteins. The antibodies were then used to isolate cDNA clones by expression screening. Here we report a detailed characterization of the protein reactive with monoclonal antibody F1-20. Immunohistochemical and biochemical analyses revealed that the F1-20 protein is synapse associated. Western blot analyses revealed that the F1-20 protein is a brain-specific polypeptide with an apparent molecular weight on SDS-PAGE of 190,000 Da. Northern blot analyses indicated that probes generated from an F1-20 cDNA clone hybridize to a single brain-specific mRNA of approximately 4.8 kilobases. In situ hybridization experiments demonstrated that F1-20 mRNA expression is neuronal specific. Northern and Western blot analyses indicated that F1-20 mRNA levels increase abruptly at postnatal day 4 and protein levels increase abruptly at postnatal day 7. This corresponds to a period of active synaptogenesis and synaptic maturation in the mouse CNS. We characterized the neuroanatomical distribution of the F1-20 protein by immunohistochemistry, and of the F1-20 mRNA by in situ hybridization. We found that the F1-20 mRNA and protein are expressed nonuniformly in brain. Variation in the expression of the F1-20 protein is complex and reveals patterns also exhibited by probes directed against other synapse-associated molecules. The highest levels of F1-20 protein are found in the cortically organized regions of the brain. The highest levels of F1-20 mRNA are found in long-distance projection neurons. There is also variation in the expression of F1-20 mRNA between different classes of large output neuron, as well as extensive variation in the expression of F1-20 mRNA between different nuclear groups.