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B Nichols

Publications and source records attributed to B Nichols.

At least 19 recordsLinked to original sources
PubMed1992

Detection of multiallele polymorphisms within gene sequences by GC-clamped denaturing gradient gel electrophoresis.

The ability to efficiently detect DNA polymorphisms is essential for the completion of a high-resolution polymorphic linkage map of the human genome. Currently the most informative polymorphisms are the multiallelic dinucleotide repeat polymorphisms. However, many gene sequences lack an associated dinucleotide repeat sequence. We used GC-clamped denaturing gradient gel electrophoresis to screen for DNA polymorphisms in the following six gene sequences: MCC, p53, prealbumin (transthyretin), rhodopsin, S-antigen, and TGF-alpha. A single-base sequence polymorphism was identified in each of these gene sequences. Some of these polymorphisms were multiallelic and highly informative. Our results demonstrate the value of denaturing gradient gel electrophoresis for both identifying and analyzing human DNA polymorphisms. The ability to detect highly informative polymorphisms within gene sequences will greatly contribute to a gene-based polymorphic linkage map.

Alleles↗
PubMed1990

Strategies in the treatment of major tissue loss and gangrene: results of 100 consecutive vascular reconstructions.

To determine the features of a successful clinical strategy, we analyzed the results of 100 consecutive lower extremity vascular reconstructions performed exclusively for tissue loss and gangrene of the legs and feet. Eighty patients underwent 100 procedures on 80 limbs. Follow-up was 95% complete (every six months, mean 2.2 years). Forty inflow procedures to the femoral artery were performed with 13 simultaneous infrainguinal bypasses. Sixty bypasses were performed from the femoral artery to the popliteal (25) or tibial arteries (35). Sixty-eight percent of the identified ulcerations healed, and limb salvage was achieved in 70% of patients by life-table analysis. The cumulative patency for all reconstructions was 48% (five years), for tibial bypasses 60% (four years). Femoropopliteal bypasses had the poorest patency and healing rates (less than 40%), while combined inflow-outflow procedures and femorotibial bypasses had the highest rates of healing (77%, 66%). There were two operative deaths, three graft infections, seven wound infections, and 12 acute graft thromboses. Vascular reconstructions for extensive tissue loss or gangrene can be performed with a morbidity and mortality comparable to procedures performed for less severe disease with a high rate of limb salvage. The long term success of surgical therapy depends primarily on the most direct revascularization of ischemic, infected tissues, using autologous conduits whenever possible.

Aged↗
PubMed1990

Biogenetic pathways of plasma membrane proteins in Caco-2, a human intestinal epithelial cell line.

We studied the sorting and surface delivery of three apical and three basolateral proteins in the polarized epithelial cell line Caco-2, using pulse-chase radiolabeling and surface domain-selective biotinylation (Le Bivic, A., F. X. Real, and E. Rodriguez-Boulan. 1989. Proc. Natl. Acad. Sci. USA. 86:9313-9317). While the basolateral proteins (antigen 525, HLA-I, and transferrin receptor) were targeted directly and efficiently to the basolateral membrane, the apical markers (sucrase-isomaltase [SI], aminopeptidase N [APN], and alkaline phosphatase [ALP]) reached the apical membrane by different routes. The large majority (80%) of newly synthesized ALP was directly targeted to the apical surface and the missorted basolateral pool was very inefficiently transcytosed. SI was more efficiently targeted to the apical membrane (greater than 90%) but, in contrast to ALP, the missorted basolateral pool was rapidly transcytosed. Surprisingly, a distinct peak of APN was detected on the basolateral domain before its accumulation in the apical membrane; this transient basolateral pool (at least 60-70% of the enzyme reaching the apical surface, as measured by continuous basal addition of antibodies) was efficiently transcytosed. In contrast with their transient basolateral expression, apical proteins were more stably localized on the apical surface, apparently because of their low endocytic capability in this membrane. Thus, compared with two other well-characterized epithelial models, MDCK cells and the hepatocyte, Caco-2 cells have an intermediate sorting phenotype, with apical proteins using both direct and indirect pathways, and basolateral proteins using only direct pathways, during biogenesis.

Alkaline Phosphatase↗
PubMed1989

Posttranslational regulation of sucrase-isomaltase expression in intestinal crypt and villus cells.

Expression and synthesis of sucrase-isomaltase (SI) were studied in human jejunum and in the colon tumor cell lines Caco-2 and HT-29. Twelve monoclonal antibodies produced against the adult human intestinal enzyme were shown to recognize specifically SI by immunoprecipitation of 14C-labeled membrane proteins, analysis of enzyme activities in the immunoprecipitates, and immunoblotting. These antibodies produced markedly different patterns of immunofluorescent staining of the intestinal mucosa. Three of them were specific for the absorptive villus cells, while the other nine also stained the luminal membrane of the proliferative crypt cells, with different intensities which paralleled their ability to recognize SI in immunoblots. Sequential immunoprecipitation of SI solubilized from purified brush borders or entire jejunum with four selected antibodies demonstrated the presence of different forms of the enzyme, expressed by either villus or crypt cells. Two immunologically distinct forms of high mannose precursor (hmP1 and hmP2) were also identified in both jejunal mucosa and colon tumor cells. They were present as monomers and their immunological differences were preserved under various ionic and pH conditions. Pulse-chase studies indicated that, in Caco-2 cells, hmP1 is converted into hmP2 within 30 min of chase, and hmP2 is then processed into the complex-glycosylated precursor destined for the brush border membrane. hmP1 was immunologically related to the mature SI present in crypt cells and lacked the epitopes specific for mature SI expressed by villus cells. These results demonstrated that sucrase-isomaltase is synthesized by both crypt and villus cells, but processing of the cotranslationally glycosylated high mannose precursor is dependent on the state of differentiation of the enterocytes. This may represent a general mechanism for the regulation of expression of differentiated cell products at the post-translational level.

Adult↗
PubMed1987

The effect of nursing care planning systems on patient outcomes.

Are written or standardized nursing care plans (NCP) as effective in enhancing the quality of patient care, and thus patient outcomes, as has been proposed for well over a decade? Data in this study did not validate the superiority of these two types of NCPs over another planning system. If the findings of this study are supported by further research, there will be scientific evidence upon which JCAH can base a reconsideration, and possible elimination, of their requirement for written/printed nursing diagnoses with corresponding nursing orders as part of nursing care planning systems.

Consumer Behavior↗
PubMed1986

Role of virus-infected mononuclear leukocytes in herpetic chorioretinitis of newborn rabbits.

The role of virus-infected mononuclear leukocytes (MNLs) in the pathogenesis of neonatal herpetic chorioretinitis in newborn rabbits was investigated. As early as 2 days after inoculating the animals' skins with type 2 herpes simplex virus (HSV-2), infectious MNLs in the infected animals' peripheral blood were found. The virus was associated, for the most part, with MNLs that belonged to phagocytic and adherent cell fractions. Observations by electron microscopy indicated that HSV-2 was actively replicating in the MNLs. It was also found that as few as 80 virus-infected MNLs injected via the right common carotoid artery were capable of inducing the chorioretinal lesions in 50% of the eyes, but that as many as 10(3) Pfu of free virus were required to produce the same lesions in the same percentage of eyes. This result clearly indicated that virus-infected MNLs were far more efficient in producing chorioretinitis than free virus, and may thus play a crucial role in the pathogenesis of herpetic chorioretinitis in newborn rabbits. When 111In-labeled virus-infected or uninfected MNLs were injected into normal rabbits via the right common carotid artery, the virus-infected MNLs localized more readily in the eye than the uninfected MNLs. The virus-infected MNLs also attached to the cultured vascular endothelial cells significantly more often than the uninfected MNLs. These results suggested that virus-infected MNLs might be easily trapped in the circulation of the eye and, in this way, produce the ocular lesions.

Animals↗
PubMed1985

Guide to early diagnosis of biliary obstruction in infancy. Review of 143 cases.

Presenting characteristics, long-term outcome, and techniques used in the diagnosis of 143 infants with suspected biliary obstruction are reviewed. Sixty-nine patients had surgically confirmed extrahepatic disease and 74 had intrahepatic disorders. A disproportionate number of infants with intrahepatic disease were boys (p = 0.013), low birthweight (p = 0.001), or had siblings with liver disease (p = 0.017). An initial total bilirubin of 20 mg/dl or greater was rare except in the intrahepatic disease category of neonatal hepatitis of known cause (p = 0.006). The initial percutaneous liver biopsy correctly predicted the ultimate diagnosis in 94 percent of all 143 patients. A methodological outline to diagnosis is presented, emphasizing early recognition of symptoms and careful follow-up with hepatobiliary imaging, liver biopsy, and surgical exploration, if required, until definitive diagnosis is made. This approach has aided us in reducing the age of diagnosis of biliary atresia from 12.8 +/- SD 7.3 weeks during the period 1971 through 1979 to 6.8 +/- SD 2.6 weeks from 1980 to 1982 (p = 0.0015). Eighteen-month survival has improved from 25 to 60 percent.

Bile Ducts↗
PubMed1984

Interview.

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Education, Nursing, Baccalaureate↗
PubMed1983

Liquid-chromatographic quantification of piracetam.

Piracetam, an analog of gamma-aminobutyric acid, absorbs maximally at 197 nm. Its molar absorptivity at 208 nm and pH 4.5 is 3576 (SD 251) L . mol-1 cm-1, approximately 45% of its absorptivity at 197 nm. Direct quantification of piracetam at 197 nm in biological extracts is complicated by the fact that many other compounds absorb between 190 and 220 nm due to carbon-nitrogen bonding. Chromatography of methanol extracts of serum and aqueous humor on a reversed-phase C-18 column developed isocratically with KH2PO4 (0.1 mol/L, pH 4.8) allows detection and quantification of 0.2 mmol of piracetam per liter. Under these conditions the retention time of piracetam is about 5 min. The detector response is linear for quantities between 5 and 15 nmol. The method is rapid, inexpensive, and convenient for the clinical laboratory.

Animals↗
PubMed1983

Surface features of the conjunctiva and cornea.

Guinea pig corneal and conjunctival surfaces were examined by transmission electron microscopy and cytochemistry. Some specimens of cornea and conjunctiva were examined morphologically; others were stained with ruthenium red or tannic acid before examination to enhance the detection of glycoproteins at cell surfaces. The epithelia were covered by microvilli and on the cornea also by microplicae. These surface projections were the shortest (150 nm) over the central cornea, and became progressively longer (approximately 300 nm) over the tarsal and fornical conjunctiva. There was a filamentous cell coat (glycocalyx) on the microvilli and microplicae that was best demonstrated in specimens stained with tannic acid. The glycocalyx extended approximately 300 nm from the tips and lateral surfaces of the microvilli and microplicae. Although there were slight local variations in its thickness, the maximum thickness of the cell coat was uniform over the cornea and conjunctiva. Heavy deposits at the cell surface after ruthenium red staining indicated that the cell coat contained many highly charged polyanions. The density of the ruthenium red stain obscured the fine structure of the filaments in the cell coat. The glycocalyx forms a scaffolding that is believed to bind mucus, with its content of immunoglobulins, by weak chemical interactions to the epithelial surface. Therefore, the microvilli, microplicae, and glycocalyx that were demonstrated in this study provide the structural framework that supports and binds a complex of related factors, including tears, mucus, and immunoglobulins, that have the common function of protecting the eye.

Animals↗
PubMed1982

Effects of prematurity on the immunologic system in human milk.

A longitudinal study of the effect of prematurity on the development of several components of the immunologic system in human milk was performed. Milk was obtained during the second through the twelfth week after parturition. The mean concentrations of lactoferrin and lysozyme were greater in preterm than in term milk during each interval of lactation. The patterns of change in these components were similar for term and preterm milk. Secretory IgA was the predominant form of IgA in preterm milk. The mean concentrations of IgA were greater in preterm milk throughout the study period. Furthermore, total and secretory IgA levels in preterm milk rose linearly during the sixth through the twelfth week, whereas the concentrations of IgA did not change in term milk during that period. In most preterm mothers, secretory IgA antibodies to Escherichia coli somatic antigens increased as lactation proceeded. These increments in specific antibodies usually did not correlate with changes in total secretory IgA. In addition, leukocyte counts in preterm milk were usually lower at two weeks and higher at 12 weeks than in term milk. Thus the concentrations of certain components of the immunologic system in human milk are altered by premature delivery. A decrease in milk volume may account for some changes, whereas certain alterations may be the result of other consequences of premature delivery or less stimulation by the premature infant.

Adult↗
PubMed1981

Validity of the Missouri Children's Picture Series as a predictor of childhood sleep disturbances.

In view of recent findings in a retrospective study by two of the authors, the present research was designed to systematically assess the validity of the Missouri Children's Picture Series sleep disturbances scale. Study I compared groups of restless sleepers and nocturnal enuretics with matched cohorts attending a summer residential program for children with communication-related disorders. Study II examined the relation of two MCPS scales to parent reports of corresponding problems, using a multitrait-multimethod matrix, individual correlations, and cluster analysis. Neither study provided convincing evidence for the validity of the sleep disturbance scale.

Adolescent↗