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Biomedical subjects

S Beck

Publications and source records attributed to S Beck.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Membrane electrophoresis of DNA.

We have separated double stranded DNA fragments by electrophoresis using a membrane instead of a gel as separating matrix. Such a membrane, containing separated DNA fragments, is suitable for subsequent hybridization analysis. The method combines electrophoretic separation and transfer onto a solid support and therefore eliminates the need for a transfer or blotting step.

Collodion↗
PubMedDate not supplied

Computed tomography in endobronchial neoplasms.

Computed tomography (CT) was performed in 86 patients with bronchoscopically proven endobronchial neoplasms. There were 76 primary and 10 metastatic lesions. CT correctly identified the abnormal airway in 95% of cases (82/86) by demonstrating either nodule, mass, or stricture. A discrete endobronchial nodule was seen in 55% (47/86). There was good morphological correlation of CT with bronchoscopic findings (89% for discrete nodule, 80% overall). Appropriate atelectasis was noted in 80% (69/86) of cases. CT is sensitive in detecting and localizing endobronchial neoplasms and correlates well with bronchoscopic findings.

Adult↗
PubMedDate not supplied

Anaemia in pregnant Ghanaian women: importance of malaria, iron deficiency, and haemoglobinopathies.

In sub-Saharan Africa, anaemia in pregnancy results from multiple causes including malaria, iron deficiency and haemoglobinopathies. In a cross-sectional study among 530 pregnant women in Ghana in November-December 1998, red blood cell indices were analysed with respect to malaria, serum concentrations of ferritin and C-reactive protein (CRP), and the haemoglobin and alpha-globin genotypes. Anaemia (haemoglobin [Hb] < 11 g/dL) was found in 54% of the women; 63% harboured malaria parasites at predominantly low numbers. Ferritin levels were considerably influenced by malaria and inflammatory processes (CRP > 0.6 mg/dL). Depending on the definition applied, the prevalence of iron deficiency ranged between 5% and 46%. The HbAS trait was observed in 14%, HbAC and elevated HbF in 7% each, and sickle cell disease in 1%. Heterozygous beta-thalassaemia was present in 1% of the women and alpha(+)-thalassaemia in 33% (29% heterozygous, 4% homozygous). Women with HbAS had higher malaria parasite densities than those with HbAA. In individuals with highly elevated HbF (> 10%), parasitaemia occurred in 27% only. Low gravidity, second trimester of pregnancy, malaria, raised CRP levels, and homozygous alpha(+)-thalassaemia were independent risk factors for anaemia in multivariate analysis. alpha(+)-Thalassaemia, however, was associated with a lesser degree of malarial anaemia when compared to non-thalassaemic women. Iron deficiency appears not to be a major health problem in this population. Haemoglobinopathies are common but, except for homozygous alpha(+)-thalassaemia, do not substantially contribute to anaemia in pregnancy. alpha(+)-Thalassaemia ameliorates malarial anaemia in pregnant women.

Anemia, Iron-Deficiency↗
PubMedDate not supplied

Sequences encoded in the class II region of the MHC related to the 'ABC' superfamily of transporters.

Class I molecules of the major histocompatibility complex (MHC) bind and present peptides derived from the degradation of intracellular, often cytoplasmic, proteins, whereas class II molecules usually present proteins from the extracellular environment. It is not known how peptides derived from cytoplasmic proteins cross a membrane before presentation at the cell surface. But certain mutations in the MHC can prevent presentation of antigens with class I molecules. In addition, mutations possibly in the MHC can affect presentation by class II molecules. Here we report the finding of a new gene in the MHC that might have a role in antigen presentation and which is related to the ABC (ATP-binding cassette) superfamily of transporters. This superfamily includes the human multidrug-resistance protein, and a series of transporters from bacteria and eukaryotic cells capable of transporting a range of substrates, including peptides.

Amino Acid Sequence↗
PubMedDate not supplied

Subduction and collision processes in the Central Andes constrained by converted seismic phases.

The Central Andes are the Earth's highest mountain belt formed by ocean-continent collision. Most of this uplift is thought to have occurred in the past 20 Myr, owing mainly to thickening of the continental crust, dominated by tectonic shortening. Here we use P-to-S (compressional-to-shear) converted teleseismic waves observed on several temporary networks in the Central Andes to image the deep structure associated with these tectonic processes. We find that the Moho (the Mohorovicić discontinuity--generally thought to separate crust from mantle) ranges from a depth of 75 km under the Altiplano plateau to 50 km beneath the 4-km-high Puna plateau. This relatively thin crust below such a high-elevation region indicates that thinning of the lithospheric mantle may have contributed to the uplift of the Puna plateau. We have also imaged the subducted crust of the Nazca oceanic plate down to 120 km depth, where it becomes invisible to converted teleseismic waves, probably owing to completion of the gabbro-eclogite transformation; this is direct evidence for the presence of kinetically delayed metamorphic reactions in subducting plates. Most of the intermediate-depth seismicity in the subducting plate stops at 120 km depth as well, suggesting a relation with this transformation. We see an intracrustal low-velocity zone, 10-20 km thick, below the entire Altiplano and Puna plateaux, which we interpret as a zone of continuing metamorphism and partial melting that decouples upper-crustal imbrication from lower-crustal thickening.

Journal Article↗
PubMedDate not supplied

A novel 25 bp tandem repeat within the human trefoil peptide gene TFF2 in 21q22.3: polymorphism and mammalian evolution.

Trefoil peptides belong to a family of small secretory proteins characterised by three intrachain disulfide bonds forming the trefoil motif (TFF-domain). They serve to maintain or repair the epithelial mucosa, and promote cell migration. They are predominantly found in gastrointestinal tissues, and are upregulated around areas of epithelial damage, and in meta- and neoplasia. The corresponding three genes are clustered in human 21q22.3. TFF2 is the only human one encoding two TFF-domains on separate exons. In between (intron 2), a novel 25 bp sequence is located that is tandemly repeated approximately 48 times, but is unique in the human genome. A diallelic polymorphism with a second allele comprising approximately 53 repeat units is present among individuals. Both alleles were cloned on BAC recombinants. In Caucasians (n = 78) the allele frequencies found are 0.85 and 0.15, respectively, representing a frequency of heterozygosity of 26%. Ape and monkey species exhibit homologous repeats of shorter total array length, whereas none is found in other mammals.

Alleles↗
PubMedDate not supplied

Anti-HIV activity of dideoxynucleosides, foscarnet and fusidic acid is potentiated by human leukocyte interferon in blood-derived macrophages.

Blood-derived macrophages were acutely infected with HIV and treated with a combination of leucocyte interferon (IFN) and five anti-HIV drugs. HIV growth was assayed by quantitation of p24 antigen in the supernatant and in some experiments by determination of reverse transcriptase activity. Both IFN and all drugs, with the exception of fusidic acid, inhibited HIV growth in a dose-dependent manner. IFN in combination with zidovudine, dideoxycytidine or fusidic acid exerted a synergistic effect on HIV titers, while IFN combined with dideoxyinosine or foscarnet had an additive effect.

Cells, Cultured↗
PubMedDate not supplied

Rescreen effect in conventional and PAPNET screening: observed in a study using material enriched with positive smears.

OBJECTIVE: To study the rescreen and PAPNET effects on enriched material derived from smears screened routinely using PAPNET and conventional microscopy. STUDY DESIGN: A series of 432 smears (containing 122 atypical squamous cells of undetermined significance [ASCUS] plus 44 at least dysplastic squamous intraepithelial lesion-positive [SIL+] ones), screened routinely with the conventional method, were rescreened using the PAPNET system. Another series of 461 smears (containing 140 ASCUS + 52 SIL+ ones) screened routinely with PAPNET were rescreened conventionally. The rescreen effect, defined as the effect of differences between the rescreen and routine screening situation, was investigated by comparing the rescreen results in both series of smears with the routine results in both series. The effect of using either method of screening was studied by comparing the PAPNET results in both series with the results of conventional screening in both series. RESULTS: The rescreen effect was statistically significant both for a higher number of smears classified as negative (less than ASCUS) and a higher number of smears classified as high grade SIL or more. PAPNET-assisted screening resulted in a significantly higher number of smears classified as high grade SIL+, although for this latter finding there is an unexplained significant difference between conventional and PAPNET-screened cases in the changes made by the cytopathologist in the cytotechnologists' diagnoses. CONCLUSION: The rescreen effect should not be ignored when enriched material is used.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Effects of enhanced conventional therapy on metabolic control in children with insulin-dependent diabetes mellitus.

We implemented a three-phase, 32-wk program to improve both self-regulation of adherence behaviors and insulin delivery in children with diabetes. Twenty children, aged 8-12 yr (mean duration 3.6 yr), enrolled. Phase 1 (wk 1-12) used behavior modification to improve diet, exercise, urine testing, and insulin adjustment, targeting an increased percentage negative urines. Feedback training and parent checks were used to improve reliability; adherence was measured using Clinitest placebos. Phase 2 (wk 13-20) was a stabilization period. Phase 3 (wk 21-32) studied the effect of insulin dose adjustment, comparing once-versus twice-daily shots in 10 pairs of children matched for %GHb. GHb, fasting plasma glucose, and lipids were measured at baseline and at the end of each phase. Results revealed a significant and sustained increase in negative urine tests, but no change in % GHb or FBG. Reliability of and adherence to urine tests were 83% and 76%, respectively. During phase 3, no significant differences were noted between groups receiving once- or twice-daily insulin injections. Thus, behavior modification resulted in increased reliability and adherence to routines, associated with a reliable increase in negative urines. This did not, however, produce changes in other control measures. Furthermore, no differences between those receiving 1 or 2 daily shots were evident.

Behavior Therapy↗
PubMedDate not supplied

Comparison of Cytobrush sampling, spatula sampling and combined Cytobrush-spatula sampling of the uterine cervix.

Since the introduction of the Cytobrush for sampling the uterine cervix, some practitioners have ceased taking a concomitant cervical scraping using a spatula. To examine whether Cytobrush sampling alone is adequate for the diagnosis of cervical lesions, the Cytobrush and spatula samples in 444 smears (most with original diagnoses of at least mild dysplasia) were analyzed separately for the presence of diagnostic cells, endocervical cells and squamous cells. Of the 412 smears showing pathologic findings (mild to severe dysplasia or worse), diagnostic cells were present in 400 Cytobrush samples and in 369 spatula samples; the combination of both samples thus gave a 3% gain in correct diagnoses as compared to use of the Cytobrush samples alone. Another 18 smears would have been underdiagnosed based only on the Cytobrush samples. Endocervical cells were present in 95.3% of the Cytobrush samples and 83.8% of the spatula samples; squamous cells were present in 93.9% of the Cytobrush samples and 96.8% of the spatula samples. Analysis confirmed that it is important that the smear should contain both endocervical and squamous cells. A positive relationship between the absence of squamous cells in the Cytobrush sample and the probability of a false-negative assessment was suggested. It thus seems inadvisable to replace the combination sampling method by Cytobrush sampling alone, which may lead to a false-negative diagnosis.

Adult↗