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Biomedical subjects

S Lambert

Publications and source records attributed to S Lambert.

At least 19 recordsLinked to original sources
PubMed1995

Continuing risk for hepatitis B virus transmission among Southeast Asian infants in Louisiana.

OBJECTIVE: Implementation and evaluation of a hepatitis B vaccination program for Southeast Asian infants in Louisiana. METHODS: A baseline seroprevalence survey of hepatitis B virus (HBV) infection in US-born Southeast Asian children was conducted in 1991 before the implementation of a vaccination program. Hepatitis B vaccination and postvaccination serologic testing of survey participants 10 years of age and younger was performed. Eighteen months after the hepatitis B vaccine was integrated into infant immunization schedules in July 1993, a vaccination coverage survey was performed. RESULTS: Baseline serologic testing was conducted on 96% of persons from 225 randomly selected households in a Southeast Asian community in Louisiana. Of 676 US-born children, 28 (4.1%) had chronic HBV infection; 61% of children with chronic HBV infection were born to hepatitis B surface antigen (HBsAg)-negative women. Among children born to HBsAg-negative women, the prevalence of chronic HBV infection increased with age, reaching 7.3% for children 13 to 16 years of age. Children born to HBsAg-negative women and living with carriers were 5.4 times more likely to have evidence of HBV infection than were children who did not live with carriers. Before the survey, only one child had received three doses of hepatitis B vaccine. In July 1993, 43% of Southeast Asian infants 9 to 18 months of age born in Louisiana had received three doses of hepatitis B vaccine. Infants who received immunizations from private providers were more likely to be fully vaccinated than were infants who received services from public sector clinics (prevalence ratio, 2.1; 95% confidence interval, 1.4, 3.1). CONCLUSIONS: HBV transmission occurs throughout childhood in US-born Southeast Asian children, and the prevalence of chronic HBV infection approaches that of the country of origin. Few US-born Southeast Asian children have received hepatitis B vaccine. Because of the high rates of early childhood HBV transmission and the high risk of chronic infection in Asian and Pacific Islander communities, prevention efforts should be enhanced to ensure that all Asian and Pacific Islander infants receive hepatitis B vaccine in the first 12 months of life and that older children are vaccinated.

Adolescent↗
PubMed1992

Insulin-like growth factor II in two human colon-carcinoma cell lines: gene structure and expression, and protein secretion.

Abnormal expression and structural modification of the IGF-II gene in correlation with high IGF-II production have recently been described in human colorectal tumors in comparison with normal adjacent tissues. Here, we have studied IGF-II in 2 human colon-carcinoma cell lines, HT29 and COLO 320DM. RFLP analyses revealed no apparent alteration at the IGF-II locus in these 2 cell lines. HT29 cells weakly expressed IGF-II mRNA in comparison with the high over-expression previously observed in some colorectal tumors, and only the 4.8-kb mRNA species was present. In addition, the serum-free medium conditioned by HT29 cells contained high IGF-II levels (approx. 900 ng/10(8) cells), as measured in a specific IGF-II radioimmunoassay (RIA). After chromatography on Bio-Gel P-60, we observed that 64% of the total IGF-II secreted by HT29 cells were present as a high-molecular-weight form of about 17 kDa. In contrast, no detectable expression of the IGF-II gene was observed in COLO 320DM cells, and low IGF-II levels were secreted by these cells in the serum-free medium, with only 9% total IGF-II represented by the large species.

Carcinoma↗
PubMed1992

Serum supply.

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Animals↗
PubMed1991

Neutron scattering studies of chromatosomes.

Neutron scattering data establish that the radius of gyration of the DNA in chicken erythrocyte chromatosome particles is significantly higher, by about 0.3 nm, than the radius of gyration of the DNA in the core particle. Corresponding information of the radius of gyration of the protein component in the chromatosomes (3.75 nm) indicated an enlargement, compared to the radius of gyration of the octamer of histone proteins both in core particles and in the histone octamer stabilised in 2 M NaCl (3.25 nm). From the latter data, we could calculate the distance in the chromatosome between the centre of mass of the linker histone and the histone octamer as 5.5 nm. These results impose severe limitations for the organisation of the 22 bp extra DNA and the possible location of H1/H5 in the chromatosome, implying that the H1/H5 is close to the centre turn of the core particle DNA.

Animals↗
PubMed1991

Tumor IGF-II content in a patient with a colon adenocarcinoma correlates with abnormal expression of the gene.

We have recently reported abnormal insulin-like growth factor-II (IGF-II) mRNA levels in a number of human colorectal adenocarcinomas. Using an IGF-II radioimmunoassay, we have now detected high levels of both 10-kDa and 7.5-kDa IGF-II species (2,370 ng/g) in a right colon tumor showing a 800-fold IGF-II gene over-expression in comparison to the normal adjacent tissue. The higher-molecular-mass form represents 74% of the total immunoreactive IGF-II detected in the tumor. This form appears to be less reactive in the radioreceptor assay than in the radioimmunoassay. The insulin-like growth factor-I (IGF-I) concentration in the tumor is low. The patient's pre-operative serum IGF-II level is not increased and the proportion of the 10-kDa species is normal. In addition, the IGF-II/IGF-I ratio is 3 in the serum and 308 in the tumor. Our results show that the very high IGF-II level produced by the tumor does not influence the seric concentration of the growth factor.

Adenocarcinoma↗
PubMed1991

Molecular basis of spectrin and ankyrin deficiencies in severe hereditary spherocytosis: evidence implicating a primary defect of ankyrin.

While varying degrees of spectrin deficiency have been found in the majority of patients with hereditary spherocytosis (HS), a combined severe deficiency of both spectrin and the spectrin-binding protein, ankyrin, has been reported only in two patients with severe HS. To elucidate the molecular basis of these protein deficiencies, we have studied the synthesis, assembly, and the mRNA levels of spectrin and ankyrin in peripheral blood reticulocytes in one of the previously reported probands. Pulse-labeling studies showed that in HS reticulocytes, the synthesis of alpha-spectrin was comparable with control reticulocytes while that of beta-spectrin was increased about fourfold, presumably reflecting increased erythropoietic drive. On the HS reticulocyte membrane, the amount of newly assembled spectrin was reduced to about half of the control values, presumably reflecting a decrease in the synthesis of the spectrin binding protein, ankyrin: the ankyrin synthesis was nearly absent in the cytosol and the amounts of membrane-associated ankyrin were reduced to about half of the normal values. The changes in the amounts of spectrin and ankyrin mRNAs quantitated by slot blot and Northern blot analyses were comparable with changes in the synthesis of these proteins: The alpha spectrin mRNA was within a control range and the beta-spectrin mRNA was slightly increased, while the amounts of ankyrin mRNA were reduced to about 50% of control values. We conclude that the primary defect underlying the combined spectrin and ankyrin deficiency is a deficiency of ankyrin mRNA leading to a reduced synthesis of ankyrin which, in turn, underlies the decreased assembly of spectrin on the membrane.

Adult↗
PubMed1991

Cellular and antibody responses directed against the HIV-1 principal neutralizing domain in HIV-1-infected children.

The principal neutralizing domain (PND) for antibody response is located within the V3 variable region of gp120 and can also stimulate T-cell responses. In some adults infected with human immunodeficiency virus (HIV) an HIV-1-specific T-cell response can be detected by demonstrating in vitro proliferation to HIV-1 proteins and peptides. In other HIV-1 infected adults an HIV-1-specific T-cell response can involve interleukin 2 (IL-2) secretion in the absence of T-cell proliferation. To elucidate the T-cell responses to PND in children, we examined the proliferative and the IL-2 secretory responses of peripheral blood lymphocytes from 19 HIV-1-infected children toward a peptide which contained a highly conserved sequence of the principal neutralizing domain of HIVMN (PND-MN). Stimulation with PND-MN induced proliferation of lymphocytes from 2 of the children and IL-2 secretion by lymphocytes from 5 of the children. In a 3-month-old infant, the in vitro cellular response to the PND-MN indicated HIV-1 infection prior to the detection p24 antigen in her serum. Although antibodies directed against PND-MN were detected in all but one of the children examined, the presence of high-affinity/avidity antibodies to the PND-MN correlated with the presence of a cellular response to PND-MN. Thus, in HIV-1-infected children an HIV-1 specific T-cell response in the absence of a proliferative response can be assessed by determination of the IL-2 secretory response and correlates with the generation of high-affinity/avidity antibodies.

Amino Acid Sequence↗
PubMed1991

Effects of apomorphine, a dopamine receptor agonist, on ocular refraction and axial elongation in a primate model of myopia.

The authors examined the effect of local administration of a dopamine receptor agonist on visual deprivation-induced excessive ocular growth and myopia. Eight rhesus monkeys were monocularly deprived of vision from birth with opaque contact lenses. Four of the monkeys received drops of 1% apomorphine HCl 2-3 times/day in the occluded eye; the four control monkeys received vehicle only. Axial lengths were determined by A-scan ultrasonography at birth and at 5-7 months of age. The authors assessed the axial elongation by comparing the postnatal growth in the axial dimension of the occluded eyes with the postnatal growth in nonoccluded eyes. In three of the four control monkeys, occlusion increased axial growth by an average of 1.3 mm. In contrast, they found that growth of the occluded and nonoccluded eyes of the apomorphine-treated monkeys was equivalent, except in one monkey whose nonoccluded eye did not develop normally and was anomalously small. At 6.5-9.5 months of age, three of four controls had myopic refractive errors (-3 to -7 diopters) in the occluded eyes; three of four of the apomorphine-treated monkeys had hyperopic refractive errors (+1-(+)3 diopters) in their occluded eyes. The occluded eye of the fourth monkey was only -0.5 diopters myopic. The findings suggest that apomorphine administration retards excessive axial elongation and the concomitant development of myopia associated with visual deprivation in primates.

Administration, Topical↗
PubMed1990

Distance estimation in the hooded rat: experimental evidence for the role of motion cues.

The role of motion cues, generated by vertical head movements, in distance estimation by hooded rats was investigated in a jumping task in which animals were trained to jump randomly varying gaps between two elevated platforms. In the first experiment it was shown that the disposition of texture cues influenced the number of head movements made prior to jumping, showing that the movements are related to visual aspects of the task. In the second experiment it was shown that stroboscopic illumination disrupted accurate jumping but animals could jump accurately to a platform when only the leading edge was visible, showing that they depend on motion cues but not motion parallax.

Animals↗
PubMed1990

Abnormal expression and structural modification of the insulin-like growth-factor-II gene in human colorectal tumors.

The insulin-like growth factor II (IGF-II) is a small protein implicated in fetal growth and development. It may play a role in the neoplastic process. The IGF-II gene is located on the short arm of chromosome II near insulin and c-Ha-ras I genes. Three distinct promoters control the transcription of this gene, leading to different IGF-II mRNA species. We have analyzed 21 human colorectal tumors and found overexpression of IGF-II in 6 of them (30%). When compared with expression in normal adjacent tissues, IGF-II mRNA increase in these tumors was either moderate (2- to 15-fold) or very marked (200- to 800-fold). In situ hybridization experiments confirmed that high IGF-II mRNA amounts were localized in cancer cells of the tumors overexpressing the IGF-II gene. In addition, DNA analysis revealed a structural modification of one IGF-II locus in one tumor characterized by very high IGF-II mRNA.

Adenocarcinoma↗
PubMed1990

Complete amino acid sequence and homologies of human erythrocyte membrane protein band 4.2.

The complete amino acid sequence for human erythrocyte band 4.2 has been derived from the nucleotide sequence of a full-length 2.35-kilobase (kb) cDNA. The 2.35-kb cDNA was isolated from a human reticulocyte cDNA library made in the expression vector lambda gt11. Of the 2348 base pairs (bp), 2073 bp encode 691 amino acids representing 76.9 kDa (the SDS/PAGE molecular mass is 72 kDa). RNA blot analysis of human reticulocyte total RNA gives a message size for band 4.2 of 2.4 kb. The amino acid sequence of band 4.2 has homology with two closely related Ca2(+)-dependent cross-linking proteins, guinea pig liver transglutaminase (protein-glutamine gamma-glutamyltransferase; protein-glutamine: amine gamma-glutamyltransferase, EC 2.3.2.13) (32% identity in a 446-amino acid overlap) and the a subunit of human coagulation factor XIII (27% identity in a 639-amino acid overlap), a transglutaminase that forms intermolecular gamma-glutamyl-epsilon-lysine bonds between fibrin molecules. The region of greatest identity includes a 49-amino acid stretch of band 4.2, which is 69% and 51% identical with guinea pig liver transglutaminase and the a subunit of factor XIII, respectively, within the regions that contain the active sites of these enzymes. Significantly, within the five contiguous consensus residues of the transglutaminase active site, Gly-Gln-Cys-Trp-Val, band 4.2 has an alanine substituted for cysteine (which is apparently essential for activity). Consistent with this active site substitution, erythrocyte membranes or inside-out vesicles, which contain band 4.2, show no evidence of transglutaminase activity by two types of in vitro assay.

Amino Acid Sequence↗
PubMed1990

cDNA sequence for human erythrocyte ankyrin.

The cDNA for human erythrocyte ankyrin has been isolated from a series of overlapping clones obtained from a reticulocyte cDNA library. The composite cDNA sequence has a large open reading frame of 5636 base pairs (bp) with the complete coding sequence for a polypeptide of 1879 amino acids with a predicted molecular mass of 206 kDa. The derived amino acid sequence contained 194 residues that were identical to those obtained by direct amino acid sequencing of 11 ankyrin proteolytic peptides. The primary sequence contained 23 highly homologous repeat units of 33 amino acids within the 90-kDa band 3 binding domain. Two cDNA clones showed evidence of apparent mRNA processing, resulting in the deletions of 486 bp and 135 bp, respectively. The 486-bp deletion resulted in the removal of a 16-kDa highly acidic peptide, and the smaller deletion had the effect of altering the COOH terminus of the molecule. Radiolabeled ankyrin cDNAs recognized two erythroid message sizes by RNA blot analysis, one of which was predominantly associated with early erythroid cell types. An ankyrin message was also observed in RNA from the human cerebellum by the same method. The ankyrin gene is assigned to chromosome 8 using genomic DNA from a panel of sorted human chromosomes.

Amino Acid Sequence↗
PubMed1989

[Odontogenic keratocysts. Review of the literature and presentation of three clinical cases with different surgical approaches].

The odontogenic keratocyst is an intra-osseous cystic lesion which generally affects the posterior part of the mandible and is characterized by the presence of a keratinized epithelium. Being asymptomatic, it is usually detected through a routine radiographic exam and it is considered to be an important lesion because of its agressiveness and its high recurrence rate. Surgery is the recommended treatment and the mode of management should take into account the agressiveness of the lesion while trying to preserve maximal anatomical and functional integrity for the patient. This paper reviews the recent literature on odontogenic keratocysts and reports our experience with three cases successfully managed in three different ways: marsupialization, decompression followed by enucleation with primary closure and finally by enucleation with packing for secondary intention healing.

Adult↗
PubMed1988

Patterns of alcohol use and psychiatric inpatient admissions.

The role of alcohol problems in psychiatric inpatient hospital admissions is not fully reflected in diagnostic statistics. A model is presented to guide the design and aid the interpretation of epidemiological research into the relationships between alcohol use and psychiatric disorder. The difficulties encountered in evaluating the role of alcohol in hospitalizations are discussed. Our preliminary research suggests that not enough attention has been paid to self-imposed abstinence from alcohol as a precipitant of symptoms and a precursor to hospitalization.

Alcohol Drinking↗
PubMed1988

Epidermal DR+T6- dendritic cells in inflammatory skin diseases.

T lymphocyte and dendritic cell subpopulations were counted in three biopsies each of endogenous eczema and pityriasis rosea and two of lichen planus and compared with previous findings in psoriatic lesions. In common with psoriasis, proportionately more CD4 T cells than CD8 T cells were DR+ in both epidermis and dermis of all lesions. In addition, total numbers of epidermal dendritic cells were significantly increased in endogenous eczema and pityriasis rosea, and variably in lichen planus lesions. Interestingly, a DR+T6- subpopulation of dendritic cells was present in varying proportions in all three skin lesion types. Electron microscopy of DR+T6- dendritic cells from psoriatic lesions, using an immunogold staining technique, showed the cells to be of the Langerhans' cell lineage. DR+T6- dendritic cells are a subpopulation of Langerhans' cells which are not specific to psoriasis, but present in the lesions of other benign, inflammatory skin conditions in which CD4 T cells are preferentially activated.

Antigens, Differentiation, T-Lymphocyte↗