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Biomedical subjects

H Fields

Publications and source records attributed to H Fields.

At least 19 recordsLinked to original sources
PubMed2002

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.

Animals↗
PubMed2001

Defining distress.

Explore the source record for details and available documents.

Animal Care Committees↗
PubMed1999

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.

Adolescent↗
PubMed1997

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.

Base Sequence↗
PubMed1996

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%).

Acute Disease↗
PubMed1994

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.

Analgesics↗
PubMed1994

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.

Hepatitis B Antibodies↗
PubMed1993

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.

Amino Acid Sequence↗
PubMed1993

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.

Acute Disease↗
PubMed1993

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.

Achievement↗
PubMed1992

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.

Acute Disease↗
PubMed1991

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.

Achievement↗
PubMed1989

Association between craniofacial morphology and fiber-type distributions in human masseter and medial pterygoid muscles.

Numerous experimental studies and clinical anecdotal evidence demonstrate a close interaction between masticatory muscle function and skeletal form. The purpose of this study was to determine whether a relationship existed between histochemical characteristics of human masseter and medial pterygoid muscles and cephalometric measurements of the 11 subjects from whom specimens were collected. Muscular specimens were obtained at the time of corrective surgery through incisions made to expose the mandibular ramus. Histochemical analysis was used to determine the size and distribution of fiber types. Angular and linear measurements were obtained from lateral cephalometric radiographs taken 1 week prior to surgery. Linear regression analysis revealed one significant negative correlation between ramus length and the percentage of Type I fibers in the medial pterygoid muscle. However, the results of this study do not support the hypothesis that a relationship exists between facial type and selected histochemical characteristics.

Adolescent↗
PubMed1983

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.

Dental Care for Persons with Disabilities↗