[Impact of amino acid sequence variation of a determinant(s) on the antigenic properties of hepatitis B virus HBsAg]

Impact of amino acid sequence variation on the antigenic properties of the surface hepatitis B virus antigen HBsAg was studied. Eleven recombinant HBsAg variants of wild (adr, ayw2, adw2, adw4, aywl, adw2) and vaccine escape (adw2 T126S, adw2 Q129L, adw2 Q129R, adw2 T143K, adw2 Q145R, aywl Q145A) were obtained. All the recombinant antigens were tested on a panel of 43 monoclonal antibodies (MAb) specific to different HBsAg determinants. Amino acid sequence variation of the a-determinant of HBsAg was shown to significantly affect its immunological responsiveness and antigenic properties. Amino acid substitution in different positions or in the same position, but for various amino acids may differently affect these properties.

Profiles of NK, NKT cell activation and cytokine production following vaccination against hepatitis B

Human natural killer (NK) cells (CD56+ CD3-) represent crucial components of the innate immune system especially against viral infections and because their activation can modulate the outcome of the adaptive immune response. NKT cells (CD56+CD3+), a lymphocyte T population characterized by expression of surface markers of NK cells, are known to be abundant in the liver and their activation could be associated with hepatic injury. Using three-color flow cytometry to measure surface receptors and intracellular cytokines, we have explored early activation signals and cytokine production in NK and NKT cells within a group of hepatitis B vaccinated and non-vaccinated individuals. A specific increase of the CD56bright cell population, the activation receptor CD69 and IFN-gamma, was observed in NK cells following incubation with recombinant HBsAg in responders to vaccination. Comparable results were observed in NKT cells showing an increment of CD69, CD25, IL-2 and IFN-gamma expression in responder subjects. These parameters were statistically diminished in non-responder individuals (p<0.05) in both groups of cells. These results demonstrate a diminished activation of these cells in non-responders to the vaccine, suggesting that NK and NKT cells play an important role in the immune response following hepatitis B vaccination.

Characterization of monoclonal antibodies and epitope mapping of the NS4 protein of hepatitis C virus

Recombinant DNA containing sequences of HCV NS4 protein was expressed in Escherichia coli cells. Six hybridoma clones producing monoclonal antibodies (MAB) to recombinant NS4 protein (rNS4), aa 1677-1756, were developed. Mapping with a panel of 33 peptides and reciprocal competitive EIA have shown that MAB obtained revealed five antigen determinants, not described earlier: MAB 3F11 and 3F12-one genotype-independent epitope of NS4A (aa 1700-1707) common for genotypes 1, 2 and 3; MAB 1D11-genotype-independent epitope (aa 1713-1728) and MAB 1D3-genotype (subtype 1b)-specific epitope of NS4B (aa 1711-1731); MAB 6B11 and C1-two conformation-dependent determinants in 5-1-1 region. These data indicate that the 5-1-1 region of NS4 protein has a complex antigenic structure and contains at least eight epitopes, including five, revealed in the present work. MAB obtained recognized native viral protein in the cytoplasm of liver cells of patients with chronic hepatitis C. The positive rates of the immunostaining for NS4 antigen using MAB 6B11, 1D11 and 3F12 were 64, 59 and 50%, respectively. It was found that 6B11 MAB to a conformation-dependent epitope much more actively interacts with native NS4 than with the recombinant protein to which MAB was developed. The epitope recognized by 6B11 MAB is highly immunogenic since it induces the B-cell response in all patients investigated with identified anti-NS4 antibodies in blood serum. The MAB panel obtained in this study may become a useful tool for the diagnostic purposes, for the investigation of NS4B function and for the host-viral interactions at the cell level.

[Characterization of a panel of monoclonal antibodies to hepatitis C NS3 recombinant protein ]

Recombinant protein rNS3 imitating helicase region (1356-1459 amino acid residues) of hepatitis C virus (HCV) was expressed in E. coli cells and used for BALB/c mice immunization. Seven hybrydoma clones producing monoclonal antibodies (MAbs) to rHS3 were obtained. All MAbs reacted in ELISA with NS3 protein from Murex anti-HCV Version III and in immunoblotting from RIBA 3. These MAbs detect 5 individual epitopes, 4 of which were conformational and 1 discontinuous. All MAbs could compete for rNS3 binding with serum antibodies from patients with chronic hepatitis C, which suggests that these MAbs can recognize the natural HCV NS3 protein.

Management of space problems in the primary and mixed dentitions

BACKGROUND

According to the Third National Health and Nutrition Examination Survey, crowding and irregularity remain a consistent problem for children. Management of space problems continues to play an important role in a dental practice. It also represents an area of major interaction between the primary provider and the specialists. This article attempts to update clinicians on the current knowledge of space management.

DESCRIPTION OF CONDITION

Proper management of space in the primary and mixed dentitions can prevent unnecessary loss in arch length. Diagnosing and treating space problems requires an understanding of the etiology of crowding and the development of the dentition to render treatment for the mild, moderate and severe crowding cases. Most crowding problems with less than 4.5 millimeters can be resolved through preservation of the leeway space, regaining space or limited expansion in the late mixed dentition. In cases with 5 to 9 mm of crowding, some can be approached with expansion after thorough diagnosis and treatment planning. Most of these cases will require extraction of permanent teeth to preserve facial esthetics and the integrity of the supporting soft tissue. Serial extraction or guidance of eruption is reserved for treatment of severe tooth-size/arch-size discrepancies. Due to variations in the timing and extraction sequence depending on the diagnosis, serial extraction should be reserved for those who can complete the treatment successfully.

CLINICAL IMPLICATIONS

The recommended timing of referring patients with moderate crowding to specialists for treatment is in the late mixed-dentition stage of development. Patients with severe crowding will require earlier evaluation for serial extraction.

Genetic heterogeneity of hepatitis G virus isolates from different parts of the world

Comparative sequence analysis of a 354 nt fragment of the NS5 region of hepatitis G virus (HGV) isolates was performed to assess two levels of HGV genomic variability: (1) heterogeneity of HGV within an infected individual, and (2) heterogeneity of different HGV isolates. Comparison of nucleotide sequences of DNA clones from two virus isolates demonstrated that in each infected individual HGV is represented by a population of virions with closely related but heterogeneous genomes (quasi-species). Phylogenetic analysis of nucleotide sequences of 42 isolates collected from 14 countries revealed less significant genome variability of HGV as compared to hepatitis C virus. Sequences of all HGV isolates fell into one group of distribution of evolutionary distances. On a phylogenetic tree all HGV sequences segregated into numerous branches. All sequences of isolates from Africa, South and South-East Asia, however, were clustered together and were separated from those of other isolates collected in Europe, North America and Central Asia.

[Immunochemical properties and specificity of monoclonal antibodies against N- and C-terminal sites of the recombinant protein of the nucleocapsid of hepatitis C virus (HCcAg)]

Highly affine murine monoclonal antibodies (MAB) to recombinant nucleocapsid (core) protein of hepatitis C virus (rHCcAg) expressed in E. coli were obtained. The MABs were analyzed by solid-phase enzyme immunoassay (EIA), immunodot, immunoblotting, and competitive immunochemical analysis. For estimating the epitope specificity of MAB, several immunoreactive fragments of different length were cloned from the HCcAg region overlapping 160 N-terminal amino acid (a. a.) residues. Use of these fragments and the competitive EIA demonstrated that MAB recognize 4 non-overlapping epitopes, 2 of which are localized in the 1-80 a. a. and 2 other in the 80-150 a. a. regions. A protocol of EIA for detecting HCcAg using MABs to two nonoverlapping HCcAg epitopes has been designed. The sensitivity of double-site sandwich is 1 ng/ml for the recombinant protein.

Fulminant hepatic failure in pregnant women: acute fatty liver or acute viral hepatitis?

BACKGROUND

Hepatitis E virus, which is endemic in our region, can cause severe liver dysfunction in pregnant women and this can be clinically confused with acute fatty liver of pregnancy.

METHODS

We studied the clinical and laboratory data as well as the maternal and fetal outcomes of 12 pregnant women presenting with fulminant hepatic failure in order to determine the etiology of the disease. The clinical diagnoses were subsequently correlated with serologic assays for acute HEV infection. All patients were severely ill with deep jaundice, grade 3-4 encephalopathy and abnormal prothrombin times.

RESULTS

A clinical diagnosis of acute viral hepatitis was made in nine patients and of acute fatty liver in the other three cases. IgM and IgG antibodies confirmed acute viral hepatitis E in six of the nine patients while one had acute hepatitis A infection. HEV IgM and IgG antibodies were, however, also positive in two of the three patients thought to have acute fatty liver. Maternal and fetal mortality were 16.6% and 50%, respectively.

CONCLUSIONS

We conclude that hepatitis E is the usual cause of acute liver failure in our pregnant women and that clinical and laboratory features do not permit accurate distinction between acute HEV infection and acute fatty liver of pregnancy. The prognosis in patients with acute HEV infection is much better than in other groups with severe liver failure (mortality 16% vs 68%).

Prevalence of hepatitis C virus infection in hemodialysis patients in Sudan

To estimate the prevalence of positivity of hepatitis C virus (HCV) antibodies in the hemodialysis population in Sudan and the risk factors of this infection in them we studied 46 hemodialysis patients (34 males, 12 females) in the Khartoum Kidney Dialysis Center (KKDC) in December 1994. Also we studied 37 healthy staff members in that unit. The blood of both groups was screened for HCV antibodies using a second generation ELISA test and confirmed by two bead supplemental assays. In the patients group, 16 cases (34.9%) were confirmed seropositive for HCV. There was a history of jaundice in four them. The mean duration on dialysis was 3.28 years in the HCV seropositive group compared with 2.2 years in the HCV seronegative group (P < 0.05). The mean frequency of blood transfusion was 2.68 units of blood in the HCV seropositive group, while it was 3.16 units in the HCV seronegative group which was not significantly different. Only two patients had high liver enzymes in the HCV seropositive groups, while there were seven patients with high liver enzymes in the HCV seronegative group. There were two staff members (5.41%) with positive HCV antibodies, but none had a history of jaundice or elevated liver enzymes. Both staff members were not involved in the direct patients care. We conclude that the prevalence of HCV antibody positivity was high in the hemodialysis population in Sudan. Nosocomial transmission may be the factor of transmission since we found no correlation with the blood transfusions.

Orthodontic diagnosis and treatment planning in the primary dentition

Early recognition of malocclusions is in the hands of the primary care providers. Pediatric and general dentists should be familiar with conditions that are known to interfere with growth and development of a child. Conditions such as early loss of primary teeth, anterior and posterior crossbites, and some Class III skeletal problems can be treated in the primary dentition to facilitate normal growth and development and offered some benefit to the patients. On the other hand, aggressive arch length modulation, Class II correction and intervention for vertical problems, including non-nutritive sucking habits, is largely unwarranted.

Suboptimal response following intradermal hepatitis B vaccine in infants

Two hundred and twenty-five infants were randomly assigned to receive 2 micrograms of plasma-derived hepatitis B vaccine (Heptavax) intradermally (ID-2), 10 micrograms intramuscularly (IM-10), or 2 micrograms intramuscularly (IM-2) in the deltoid region at birth, 2 and 4 months. At 6 months, ID-2 infants were less likely to have developed > or = 10 mIU ml-1 of antibody to hepatitis B surface antigen (anti-HBs) than IM-10 infants (91 versus 100%; p = 0.02) and had a lower geometric mean concentration of anti-HBs (312 mIU ml-1 versus 2248 mIU ml-1; p < 0.01). At 6 months IM-10 infants had significantly lower mean weights and lengths than infants receiving 2 micrograms doses of vaccine. Intramuscular administration of 2 micrograms and 10 micrograms doses of Heptavax in the deltoid of young infants was well tolerated and effective; however, intradermal administration of Heptavax provided no immunological benefit over intramuscular administration and resulted in significantly higher rates of induration and persistent hyperpigmentation. Intramuscular immunization at birth, 2 and 4 months is an acceptable, effective alternative schedule for immunizing infants.

Pain modulation and the action of analgesic medications

A general approach to improving the treatment of patients with post-herpetic neuralgia is outlined. Pain-generating processes initiated by injury to peripheral nerve and new treatments that target these processes are discussed. Another described approach is to use knowledge of central nervous system pain-modulating networks to improve the effectiveness of centrally acting analgesics such as opioids and tricyclic antidepressants.

Unique preS sequence in a gibbon-derived hepatitis B virus variant

A unique hepatitis B virus (HBV) variant has been identified in a gibbon (Hylobates lar) which could be passed to a chimpanzee by experimental inoculation. This HBV variant had been shown to have no reactivity to a monoclonal anti-preS2 antibody (preS2 mAb 116-34) differentiating it from all human HBV specimens tested. This gibbon sera also was not recognized by an anti-preS1 mAb which binds the preS1 hepatocyte receptor region, amino acids 27-35. In this paper, we report the DNA sequence of the gibbon HBV PreS gene. The lack of preS2 mAb (116-34) binding can be explained by a unique nucleotide substitution of A for C in the second codon of the preS2 region leading to the replacement of glutamine with lysine. Two other unique changes were observed at the seventh and 24th amino acid positions in the preS2 gene leading to a substitution of a valine for threonine and alanine, respectively. Unlike all human derived HBV sequences in the preS1 region, the gibbon HBV had a glutamic acid instead of an aspartic acid at amino acid residue 27. Another unique substitution was a leucine for alanine at preS1 position 33. These amino acid changes in the gibbon HBV may explain its unique preS mAb reactivity.

Aetiology of acute sporadic non-A, non-B viral hepatitis in India

Non-A, non-B (NANB) hepatitis viruses are now classified as hepatitis E (enterically transmitted) and hepatitis C (parenterally transmitted). India experiences a large number of epidemics of the enteric disease every year. In addition, about 70% of the sporadic cases among adults are also due to NANB hepatitis. With the availability of an immunoblot assay for the detection of anti-HEV-IgM and the polymerase chain reaction (PCR) for the detection of HCV-RNA, serum samples from epidemic and sporadic NANB patients were screened for these markers. We found that a large number of cases from the epidemics were HEV, though a few remained undiagnosed, while of the sporadic cases only a few could be diagnosed as HCV or HEV; a large proportion remained undiagnosed.

A developmental study of specific spelling disability

Previous studies have identified a group of individuals with specific problems in spelling, and compared them to a group with problems in reading and spelling. Those who are poor at reading and spelling are thought to have more severe underlying language problems. This study compared the cognitive abilities of three groups of children: one specifically spelling disabled, one spelling and reading disabled, and one control group without reading or spelling problems. The groups were identified at age 14. A five-year retrospective analysis of their performance revealed that both of the disabled groups had been significantly poorer than the controls, not only in spelling but also in reading. Both the disabled groups showed other signs often associated with dyslexia such as poor WISC-R Coding and Digit Span. Analyses of their spelling errors did not reveal the superior phonetic abilities which some other studies have found to differentiate specifically spelling disabled from reading + spelling disabled groups. The specific spelling disabled group did show some evidence of superiority in Verbal IQ subtests. These results are consistent with the idea that specific spelling disability is a residual problem of individuals who, possibly by means of underlying verbal strengths, have managed to compensate for earlier reading difficulties.

Epidemiology and long-term consequences of hepatitis delta virus infection in the Yucpa Indians of Venezuela

To define better the epidemiology and clinical impact of hepatitis delta virus (HDV) infection among hepatitis B virus (HBV) carriers in less developed countries, the authors prospectively studied a cohort of 216 Yucpa Indian HBV carriers in Venezuela. HBV carriers were followed regularly between 1983 and 1988 by physical examination, laboratory testing for liver enzymes and HBV and HDV markers, and epidemiologic history. Among the cohort, 74 (34%) were initially positive for HDV infection, and 35 additional persons became infected during the study. Risk factors for new HDV infection included living in southern Yucpa villages; being young adults (15-19 years) or young children (1-9 years), and living in a household with a person with acute HDV infection. Persons with HDV infection were at high risk of developing chronic liver disease; 56% of HDV-infected persons had moderate-to-severe chronic liver disease at the end of the study compared with none of the HBV carriers without HDV infection. Mortality rates were 6.9% and 8.8% per year, respectively, among initially HDV-positive HBV carriers and those with new HDV infection, because of rapidly progressive chronic liver disease and fulminant hepatitis; mortality was significantly lower in HBV carriers without HDV infection and in non-HBV carriers. HDV superinfection is a devastating disease in HBV carriers in tropical South America. Prevention of HBV infection with hepatitis B vaccine is the best available tool to reduce the impact of this problem.

Identification of a group of children with dyslexia by means of IQ-achievement discrepancies

The reading and spelling abilities of 462 school children of mean age 8 years 7 months were examined in relation to their intellectual abilities (as assessed by the WISC-R) by means of cluster analysis. The analysis identified five groups. In one group reading and spelling were considerably poorer than their intellectual abilities. The performance of the five groups was examined on a number of cognitive tests commonly associated with dyslexia. The group identified as having significant discrepancies showed the poorest performance on many of these tests. In addition this group showed other features associated with dyslexia. Further analysis indicated the existence of two subgroups which differed significantly in performance on the cognitive tests.

Nurse education in the market place

The education and training of health service professionals and non-professionals is set to be driven by a market-place philosophy which will exert and endorse competition and control via rapidly evolving change and reform. Helen Field's article seeks to provide an outline of such reform within the National Health Service education and training arena. In particular, it considers how the education of nurse professionals will fare in a system which focuses more accurately on efficiency, cost effectiveness, quality and marketing of educational provision.

Use of immunogold preembedding technique to detect hepatitis A viral antigen in infected cells

Localization of virus and viral antigen in cell cultures infected with a rapidly replicating isolate of strain HM-175 of hepatitis A virus (HAV; pHM-175) was accomplished by using immunogold probes. Cells infected under one-step growth curve conditions were prefixed with 2% paraformaldehyde and 0.1-0.001% saponin at appropriate times postinfection for detection of maximum virus and viral antigen. An indirect labeling technique was employed using monoclonal antibody to HAV followed by 5 nm gold-antimouse IgG conjugate. Cells were then fixed by standard electron microscopy techniques and thin sectioned. This prefixation technique allowed penetration of the immunogold probes and moderate preservation of ultrastructure. Within infected cell cytoplasm, numerous antigenic sites were labeled with six to 200 gold particles. Two types of cells were infected with HAV and somewhat different results were obtained with the two cell types. In BS-C-1 cells, where a cytopathic effect (CPE) was not observed, myelin figures were immunogold labeled or frequently were located near immunogold-labeled sites. Vesicles containing viruslike particles (14-22 nm) were also observed. A significant observation in infected FRhK-4 cells was the presence of multivesicular bodies labeled with immunogold. Microfilaments were commonly seen near the multivesicular bodies. Our results demonstrate that the choice of prefixation method for immunogold labeling should be empirically determined for the cell type and condition.

Hepatitis delta virus infection and Labrea hepatitis. Prevalence and role in fulminant hepatitis in the Amazon Basin

To define more exactly the epidemiology of delta virus infection and confirm its role in causing fulminant Labrea hepatitis in the Amazon Basin, we studied the prevalence of delta virus infection among persons with acute and chronic hepatitis B virus infection in the Boca do Acre district of the southern Amazon Basin. Delta virus infection was found in 24% of asymptomatic hepatitis B virus carriers, 29% of acute nonfulminant hepatitis B cases, 74% of fulminant hepatitis B cases, and 100% of chronic hepatitis B cases. Chronic delta virus infection occurred primarily in older children and adults, while acute and fulminant delta virus infection occurred in young children as well. In fulminant hepatitis cases, delta virus superinfection of hepatitis B virus carriers was the most common serological pattern; histopathologic examination showed features identical to those described in fulminant hepatitis cases of similar etiology in Colombia and Venezuela. Delta virus infection is highly endemic in the southern Amazon Basin and is the principal cause of Labrea hepatitis.

A laboratory study of changes in vertical dimension using a compression molding and a pour resin technique

A controlled investigation was conducted to compare the increase in vertical dimension of complete dentures after processing with a compression molding technique and with a pour resin technique. The smallest increase in vertical dimension of occlusion was obtained with the compression molding technique.

Hereditary hemorrhagic telangiectasia: prosthetic management and considerations

The dentist should be aware of the signs, symptoms, and significance of hereditary hemorrhagic telangiectasia. A patient who had unusual involvement of the masticatory mucosa and for whom construction and function of complete dentures did not result in discomfort or oral bleeding is described. Dentures may have a positive effect on the size and number of telangiectasias. A gradual decrease in the size of a nodular lesion of the mandibular edentulous ridge is documented over a 3-year period.

A laboratory study of changes in vertical dimension using acrylic resin and porcelain teeth

A controlled investigation was conducted to compare the increase in vertical dimension of complete dentures after processing using acrylic resin and porcelain teeth. The smallest increase in vertical dimension was obtained using acrylic resin teeth.

A comparative study of changes in vertical dimension of occlusion using different investing mediums

A controlled investigation was conducted in which 50 sets of dentures were processed with different investing mediums. The most accurate results in maintaining the vertical dimension of occlusion of dentures during processing were obtained with artificial stone and a layer of silicone rubber.

Comparison of disclosing media used for adjustment of removable partial denture frameworks

An investigation was conducted to evaluate eight disclosing media for the detection of binding or interference regions on removable partial denture frameworks. The aerosol spray media were judged to be the most acceptable of those tested because they are easy to use and afford minimal waste; they also adhere well to removable partial denture metals and while easily removed, they are not washed away by excess saliva.

Combination prosthesis for optimum esthetic appearance

A method of treatment that combines the advantages of both a removable partial denture and a fixed partial denture is described. The indications, contraindications, advantages, and special considerations are discussed. The procedures necessary for treatment of patients are described. Our observations indicate that this is an acceptable mode of treatment for those patients in need of this type of prosthesis.

Videotape modeling of the child dental patient

One week before their first dental visit, 36- to 60-month-old children were shown a videotape to model their behavior in the dental situation. The behavior was then rated for three visits. The children who had been modeled did not behave significantly better than either children who had no previous contact with the dental setting or children who had visited the reception room one week before their first dental visit.

Hbc ag, anti-HBC, and DNA polymerase activity in transfused recipients followed prospectively

Hepatitis B core antigen, antibody to core antigen, and DNA polymerase activity were measured in sera from a select group of post-transfusion hepatitis B patients who had been followed prospectively following blood transfusion. Preliminary results of this study have revealed (1) that RIA testing of blood would not eliminate but would reduce post-transfusion hepatitis B infections by about 50 per cent; (2) that infection with HB virus is modified or aborted in the presence of pre-existing antibody to HB surface antigen; and (3) that transfusion of blood containing anti-HBs does not increase the risk of post-transfusion hepatitis B. HBc Ag and/or DNA polymerase activity were observed in the sera of all recipients tested who developed liver enzyme abnormalities along HBs Ag and anti-HBc. DNA polymerase activity usually occurred in the early stages of incubation before the transaminase became abnormal, whereas HBc Ag was more often associated with increasing enzymatic evidence of liver damage, suggesting release of core structures from the hepatocytes. The presence of DNA polymerase without detectable HBc Ag may be due to the presence of intact Dane particles in the sera, preventing recognition of the core antigen. No serological evidence of hepatitis B was observed in the sera of 24 other recipients who developed abnormal transaminases. Immunoelectron microscopy of these same sera revealed evidence of exposure to hepatitis A antigen following transfusion in at least two recipients.