Venus's southern polar vortex reveals precessing circulation.

Initial images of Venus's south pole by the Venus Express mission have shown the presence of a bright, highly variable vortex, similar to that at the planet's north pole. Using high-resolution infrared measurements of polar winds from the Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument, we show the vortex to have a constantly varying internal structure, with a center of rotation displaced from the geographic south pole by ~3 degrees of latitude and that drifts around the pole with a period of 5 to 10 Earth days. This is indicative of a nonsymmetric and varying precession of the polar atmospheric circulation with respect to the planetary axis.

South-polar features on Venus similar to those near the north pole.

Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright 'dipole' feature surrounded by a cold 'collar' at its north pole. The polar dipole is a 'double-eye' feature at the centre of a vast vortex that rotates around the pole, and is possibly associated with rapid downwelling. The polar cold collar is a wide, shallow river of cold air that circulates around the polar vortex. One outstanding question has been whether the global circulation was symmetric, such that a dipole feature existed at the south pole. Here we report observations of Venus' south-polar region, where we have seen clouds with morphology much like those around the north pole, but rotating somewhat faster than the northern dipole. The vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper. The spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition.

Regulatory roles for the homeodomain and C2H2 zinc finger regions of Cryptococcus neoformans Ste12alphap.

The STE12alpha gene of Cryptococcus neoformans encodes a protein containing both homeodomain and zinc finger regions. As homeodomains and zinc finger regions are important domains for the function of many transcription factors, we used site-specific mutagenesis to delineate the roles of these two domains. The homeodomain and zinc finger regions are each important for the function of Ste12alphap. DNA binding ability, mating frequency, and haploid fruiting capability were reduced in strains with mutations in the homeodomain, whereas virulence and capsule size in the mouse brain were increased. In contrast, mutations in the zinc fingers region resulted in decreased virulence, reduced capsule size in the mouse brain and decreased gene expression of capsule associated genes. In addition, phospholipase activity was increased in the zinc finger mutants. Taken together, most of the phenotypes previously observed in the ste12alpha deletion strains were reproduced in these two types of mutants. However, unlike mutations in the homeodomain/zinc finger region, complete deletion of STE12alpha caused a severe reduction in virulence and a decrease in phospholipase activity. These data suggest that region(s) other than the homeodomain and zinc finger regions of Ste12alphap contribute to the variable influences on the different phenotypes observed in C. neoformans.

A comparison of two oral ketamine-diazepam regimens for the sedation of anxious pediatric dental patients.

PURPOSE: This study compared 2 oral ketamine-diazepam regimens (8 mg/kg and 10 mg/kg of ketamine in combination with 0.1 mg/kg diazepam) in preschool age children with respect to physiological, behavioral and amnestic parameters. METHODS: Twenty-five children completed the double-blind, crossover design. Physiologic, behavioral and amnestic effects were evaluated. RESULTS: ANOVA demonstrated significant changes in systolic blood pressures and heart rates in both the 8 mg/kg group and 10 mg/kg group (P < 0.05), as well as significant changes in diastolic blood pressures in the 10 mg/kg group (P < 0.05). However, these changes were not clinically significant. Success rates were 28% for the 8 mg/kg dosage and 44% for the 10 mg/kg dosage. There was a cumulative vomiting rate of 50% and a psychic phenomena rate of 10%. There were no statistically significant differences between the two dosages with regard to success rates, postoperative vomiting, or psychic phenomena using McNemar's test. CONCLUSIONS: There is no advantage of 10 mg/kg dose of ketamine over the 8 mg/kg dose. Ketamine did not demonstrate amnestic effects in this study. There were statistically but no clinically significant changes in physiological parameters in either group. This study does not support the use of either 8 mg/kg or 10 mg/kg oral ketamine for the sedation of uncooperative children.

Nanoengineered structures for holding and manipulating liposomes and cells.

We describe the fabrication of nanoengineered holding pipets with concave seating surfaces and fine pressure control. These pipets were shown to exhibit exceptional stability in capturing, transporting, and releasing single cells and liposomes 1-12 microm in diameter, which opens previously inaccessible avenues of research. Three specific examples demonstrated the utility and versatility of this manipulation system. In the first, carboxyrhodamine was selectively incorporated into individual cells by electroporation, after which nearly all the medium (hundreds of microliters) surrounding the docked and tagged cells was rapidly exchanged (in seconds) and the cells were subsequently probed by laser-induced fluorescence (LIF). In the second study, a single liposome containing carboxyrhodamine was transported to a dye-free solution using a transfer pipet, docked to a holding pipet, and held firmly during physical agitation and interrogation by LIF. In the third study, pairs of liposomes were positioned between two microelectrodes, held in contact, and selectively electrofused and the resulting liposomes undocked intact.

Manipulating the genetic identity and biochemical surface properties of individual cells with electric-field-induced fusion.

A method for cell-cell and cell-liposome fusion at the single-cell level is described. Individual cells or liposomes were first selected and manipulated either by optical trapping or by adhesion to a micromanipulator-controlled ultramicroelectrode. Spatially selective fusion of the cell-cell or cell-liposome pair was achieved by the application of a highly focused electric field through a pair of 5-micrometer o.d. carbon-fiber ultramicroelectrodes. The ability to fuse together single cells opens new possibilities in the manipulation of the genetic and cellular makeup of individual cells in a controlled manner. In the study of cellular networks, for example, the alteration of the biochemical identity of a selected cell can have a profound effect on the behavior of the entire network. Fusion of a single liposome with a target cell allows the introduction of the liposomal content into the cell interior as well as the addition of lipids and membrane proteins onto the cell surface. This cell-liposome fusion represents an approach to the manipulation of the cytoplasmic contents and surface properties of single cells. As an example, we have introduced a membrane protein (gamma-glutamyltransferase) reconstituted in liposomes into the cell plasma membrane.

Chemical transformations in individual ultrasmall biomimetic containers.

Individual phospholipid vesicles, 1 to 5 micrometers in diameter, containing a single reagent or a complete reaction system, were immobilized with an infrared laser optical trap or by adhesion to modified borosilicate glass surfaces. Chemical transformations were initiated either by electroporation or by electrofusion, in each case through application of a short (10-microsecond), intense (20 to 50 kilovolts per centimeter) electric pulse delivered across ultramicroelectrodes. Product formation was monitored by far-field laser fluorescence microscopy. The ultrasmall characteristic of this reaction volume led to rapid diffusional mixing that permits the study of fast chemical kinetics. This technique is also well suited for the study of reaction dynamics of biological molecules within lipid-enclosed nanoenvironments that mimic cell membranes.

Examination of esthetic improvement and surface alteration following microabrasion in fluorotic human incisors in vivo.

Improvement of appearance and alteration in surface enamel was evaluated following microabrasion of teeth with differing degrees of fluorosis stain in vivo. Eighty-two fluorotic permanent maxillary central incisors from 41 patients were divided into categories of mild (32), moderate (30), and severe (20). Teeth received 30-sec applications of PREMA until no stain remained or for a maximum of 10 min of treatment. Ten teeth needed only 5 min of treatment. All others received the maximum. Standardized intraoral photographs and duplicate polysiloxane impressions were taken prior to treatment, after 5 and 10 min of treatment, and at least 4 days after treatment. Slides were randomized and viewed independently by two standardized observers and rated for area of white spot lesions (WS), stain amount (SA), and stain intensity (SI). The Wilcoxon's signed rank test indicated a significant difference in the area of WS (P < 0.05) and SA and SI (P < 0.005) from pretreatment to successive ratings. Kruskal-Wallis analysis revealed significant differences among the three severity groups for amount of WS, SA, and SI (P < 0.005). Mildly stained teeth had the best esthetic result, moderately stained teeth improved but continued to demonstrate WS and staining, and severely stained teeth showed some improvement, but more than 50% of the surface had WS and > 25% of the surface was stained. SEMs at 10X magnification were made of the models and randomly rated for type, depth, description, and area of surface defects by the two observers. Mild teeth showed no significant changes from pretreatment to 10 min of treatment. Moderate and severe teeth showed no significant change in type and depth of defects from pretreatment to 10 min of treatment but were significantly worse in description and area of defects. Despite esthetic improvement in all groups, moderate and severe teeth showed more defective surfaces following microabrasion. This technique can only be recommended as definitive treatment for teeth with mild fluorosis.

A comparison of two oral ketamine-diazepam regimens for sedating anxious pediatric dental patients.

This double-blind, crossover study assessed physiology and behaviour following administration of two oral ketamine-diazepam sedation regimens (4 mg/kg and 8 mg/ kg ketamine in conjunction with 0.1 mg/kg diazepam). Clinical success was achieved in 50% of sedations with 4 mg/kg and 78% of sedations with 8 mg/kg with no significant differences between the two regimens (Fisher's exact test). Within the crossover group, clinical success was achieved in 56% of sedations with 4 mg/kg and 87% of sedations with 8 mg/kg with no significant differences between the two regimens (Fisher's exact). Although clinically insignificant, ANOVA revealed statistical elevations in blood pressures and heart rates and decreases in oxygen saturations (P < 0.05). The 4-mg/kg regimen resulted in more negative behavior and less sleep. The 8-mg/kg regimen resulted in less negative behavior and more sleep.

Management of trauma to primary and developing teeth.

Traumatic dental injuries to the young child can present both diagnostic and therapeutic challenges. Luxation injuries to the primary dentition are the most common injuries. Yet, they are the most controversial with regard to definitive treatment, prognosis, and sequelae. Damage to the developing teeth subsequent to primary tooth injury is often unavoidable and has permanent effects on the dentition. Diagnostic criteria, treatment options, and outcomes are presented in this article; however, treatment decisions are often based on patient behavior.

Evaluation of morphine as compared to meperidine when administered to the moderately anxious pediatric dental patient.

This investigation evaluated two narcotic regimens used to sedate pediatric dental patients who previously demonstrated uncooperative behavior. One consisted of submucosal morphine (0.15 mg/kg), and the other, oral meperidine (2.2 mg/kg); both were administered in combination with oral promethazine (1.1 mg/kg). Patients 2-7 years old were sedated with one of the two regimens and videotaped during dental treatment. If sedation was successful, the child received the other regimen at the next appointment, resulting in a total of 42 sedations in 29 children. Later, patient behavior was rated blindly by two independent observers viewing tapes of specific events during dental treatment. Fourteen of 23 (61%) patients receiving morphine and 11 of 19 (58%) patients receiving meperidine were sedated successfully. Vital signs, including pulse, respirations, blood pressure, and oxygen saturation were monitored and remained stable for both groups. ANOVA for repeated measures showed no significant differences for any vital sign in either group across time. Wilcoxon's signed rank test revealed significant improvement for the patients successfully treated in both groups when presedation behavior was compared with behavior during the events of rubber dam application, operative, restorative treatment, and exit (meperidine, P < 0.005 and morphine, P < 0.001). Improvement also was seen in the meperidine group for the event of local anesthesia (P < 0.01). Chi-square analysis showed no statistically significant differences in effectiveness or safety between the two sedative regimens.

Characterisation and biological activity of monoclonal antibodies specific for Pasteurella haemolytica A1 capsule and lipopolysaccharide.

Monoclonal antibodies (mAb) against both Pasteurella haemolytica A1 capsule and lipopolysaccharide (LPS) were produced. Anti-capsule mAb reacted with the homologous A1 serotype only, whereas mAb against LPS reacted with P. haemolytica serotypes A2, A5, A8, A12, A14 and A16 but not with 33 bacterial species or rough LPS mutant strains tested. Both capsule and LPS antigens were visualised on the surface of bacteria by immunogold electron microscopy. Neither of the mAbs demonstrated antibody-dependent complement-mediated killing in vitro but both facilitated phagocytosis in vitro.

Antigenic analysis of iron-regulated proteins in Pasteurella haemolytica A and T biotypes by immunoblotting reveals biotype-specific epitopes.

The antigenic relationships of the iron-regulated proteins (IRPs) in Pasteurella haemolytica A and T biotype strains were examined by SDS-PAGE and immunoblotting. P. haemolytica cells of the A biotype, grown under conditions of iron-limitation, expressed two IRPs, of 35 and 70 kDa. All T biotype strains expressed IRPs with slightly different molecular masses of 37 and 78 kDa. Immunoblotting of all 16 P. haemolytica serotypes was carried out using a panel of polyclonal and monoclonal antibodies raised against serotype A2 antigens. Polyclonal antibodies revealed inter-serotype cross-reactivity towards the 35 and 70 kDa IRPs within the A biotype but no cross-reactivity against a T biotype protein in the 78 kDa region. Monoclonal antibody against the 35 kDa antigen reacted only with the A biotype 35 kDa IRP. Identical profiles were obtained for 10 field isolates of serotype A2, further emphasizing the antigen conservation within the A biotype. These findings reinforce the view that the A and T biotypes of P. haemolytica should be considered as separate species and suggest that IRPs from single A and T biotype strains incorporated into a vaccine might provide cross-protection against all P. haemolytica serotypable strains. Similar studies on the IRPs of 10 untypable strains revealed some of these to have different antigenic reactivities from those observed within the A and T biotypes.

Identification and localization of an iron-regulated 35 kDa protein of Pasteurella haemolytica serotype A2.

Iodination of intact Pasteurella haemolytica serotype A2 cells labelled a sub-set of total cellular proteins. Comparison of the autoradiographic patterns obtained from iodinated cells grown on complete medium and on iron-depleted medium showed that expression of three proteins, of 100, 70 and 35 kDa, respectively, was increased by growth under iron-depleted conditions. Of these proteins, that of 35 kDa had not been reported previously. Like the 100 and 70 kDa proteins, the 35 kDa protein was expressed in natural infections, since it was recognized by antiserum from sheep that had recovered from an experimental infection with P. haemolytica A2. The 35 kDa protein was partially purified by reverse-phase HPLC and was found to be antigenic in both sheep and mice. A monoclonal antibody that was specific for the 35 kDa protein was used to identify the cellular location of the protein by immunoblotting of cell fractions enriched for particular cellular components. This demonstrated that the 35 kDa protein was located mainly in the periplasm.

Production of mouse monoclonal antibodies to Pasteurella multocida type A and the immunological properties of a protective anti-lipopolysaccharide antibody.

Eight monoclonal antibodies (MAbs) were produced from mice immunised with whole cells of heat-killed Pasteurella multocida type A which had been cultured under iron-restricted conditions. The MAbs were selected by an enzyme-linked immunosorbent assay (ELISA) in which the antigen consisted of whole bacteria of the immunising strain. Their reactivity was investigated further by immunoblotting, indirect haemagglutination, a complement-mediated bactericidal assay and passive protection of mice. One of the eight MAbs was shown by immunoblotting to react with lipopolysaccharide (LPS), was bactericidal, and completely protected mice against homologous challenge with 10 LD50 of live bacteria. This MAb was selected for further study. Its reaction with LPS of 17 type-A strains and of single strains of types B, D and E was investigated by immunoblotting. Strains that reacted with the anti-LPS MAb in immunoblots were susceptible to its bactericidal activity and gave high ELISA absorbances. Those that did not react were not susceptible to its bactericidal activity and gave low ELISA readings. The relation between bactericidal activity and ELISA absorbance was highly significant (p less than 0.001). Five of the strongly reacting heterologous strains and one non-reacting strain were selected as challenge organisms in a passive protection experiment: only the mice receiving the reacting strains were protected.

Current trends in behavior management techniques as they relate to new standards concerning informed consent.

Standards governing informed consent are changing across the United States, and these changes have potential impact on the techniques of behavior management used by pediatric dentists. The purpose of this study was to determine pediatric dentists' awareness of standards of informed consent in the state in which they practice, as well as the impact of the professional community standard versus the reasonable patient standard on their use of certain behavior management techniques. A stratified random sample of 502 practitioners was selected from the total membership of the American Academy of Pediatric Dentistry; 292 returned surveys provided data related to behavior management techniques, consent standards, and demographic variables. These were analyzed by Chi-square (P less than 0.05). Results revealed that 73% of the respondents do not know which consent standard is in effect in the state in which they practice; 50% do not get verbal consent; and 80% do not get written consent to use the specific management techniques. There is a lack of knowledge on the part of some pediatric dentists concerning the changing laws governing informed consent and a reluctance to acknowledge the implications that these changes would have on behavior management techniques.

Polymorphism of a 35-48 kDa Plasmodium falciparum merozoite surface antigen.

Glycoproteins of the asexual blood stages of Plasmodium falciparum were labelled with radioactive glucosamine and analysed by two-dimensional electrophoresis. Four major glycoproteins were detected in all eight parasite isolates studied. Two of the glycoproteins, designated GP2 and GP4, were invariant among the isolates, while the other two GP1 and GP3 were found to be polymorphic in both their biochemical and antigenic properties. By immunoblotting and immunoprecipitation with specific monoclonal antibodies, the two polymorphic glycoproteins were identified as surface antigens of merozoites.

46-53 kilodalton glycoprotein from the surface of Plasmodium falciparum merozoites.

A 46-53 kDa glycoprotein antigen of Plasmodium falciparum merozoites has been identified using a murine monoclonal antibody that inhibits infection of human erythrocytes in vitro. Immunofluorescence screening with the antibody of greater than 250 isolates of the parasite finds the inhibitory epitope expressed by only 18% of strains. The glycoprotein is metabolically labelled with methionine, cysteine, histidine and glucosamine but incorporates little lysine or leucine. It is synthesized early in schizogony and remains, without any apparent processing, on the surface of released merozoites where it is demonstrated by immuno-electronmicroscopy and also by vectorial radio-iodination.