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Biomedical subjects

K Wood

Publications and source records attributed to K Wood.

At least 73 records · Page 4Linked to original sources
PubMed1994

Characterization of sequences within heparin-binding EGF-like growth factor that mediate interaction with heparin.

Heparin-binding (HB) epidermal growth factor (EGF)-like growth factor (HB-EGF), a member of the EGF protein family, is a potent mitogen for fibroblasts, smooth muscle cells, and keratinocytes that was initially identified as a secreted product of macrophage-like cells. HB-EGF and EGF appear to act on target cells utilizing the same receptor, but HB-EGF is distinguishable from EGF by its strong affinity for heparin. To facilitate studies of structure-function relationships in HB-EGF, a bacterial recombinant expression system was established that produced biologically active HB-EGF with the expected disulfide bonding pattern. Mutagenesis and protease digestion studies of the recombinant HB-EGF, coupled with heparin-binding analyses of synthetic peptides, indicated that the sequences within HB-EGF mediating its interaction with heparin are located primarily in a stretch of 21 amino acids characterized by a high content of lysine and arginine residues. Most of this heparin-binding domain lies in an amino-terminal region of HB-EGF that has no counterpart in EGF, but a portion of the 21-residue sequence extends into the EGF-like region of HB-EGF. In addition, the mutagenesis and synthetic peptide studies indicated that sequences in HB-EGF lying outside of the 21-residue stretch can also influence the interaction with heparin. Finally, a synthetic peptide derived from the 21-residue stretch was found to compete with HB-EGF for binding to Chinese hamster ovary cells, suggesting that the heparin-binding sequences in HB-EGF may also mediate the interaction of this factor with cell surface heparan sulfate proteoglycan.

Amino Acid Sequence↗
PubMed1994

Reconstruction of human skin from glycerol-preserved allodermis and cultured keratinocyte sheets.

The aim of this project was to reconstruct human skin from glycerol-preserved dermis and layers of cultured keratinocytes for use in the treatment of deep burns and ulcers. Glycerol-preserved cadaver skin from the Euro Skin Bank was treated with Dispase II or PBS, under various conditions, to find the best method of retaining the physical structure of the dermis while removing the epidermis and remnants of dead dermal cells which might provoke an allogeneic reaction in a graft recipient. Monoclonal antibodies LH39 and LH7.2, with specificity for basement membrane determinants, showed that treatment with Dispase II resulted in separation of the epidermis from the dermis with concomitant loss of all cellular elements from the dermal layer (as judged by H and E staining). However, when sheets of cultured keratinocytes were applied to the treated dermis and cultured for several days, the keratinocytes attached and regenerated a new basement membrane.

Cells, Cultured↗
PubMed1994

Intravenous cholangiography in preoperative assessment of patients considered for laparoscopic cholecystectomy.

This study examines the role of intravenous cholangiography in the preoperative assessment of the first 100 patients considered for laparoscopic cholecystectomy at this institution. Intravenous cholangiography detected common bile duct (CBD) stones in 10 patients, of whom only five had a dilated CBD (> 8 mm). There were no cases of inadequate visualization of the CBD using IVC and no allergic reactions to the contrast medium. All CBD stones were confirmed by either endoscopic retrograde cholangiopancreatography (ERCP) or exploration of the CBD. There have been no cases of missed CBD stones during a follow-up period of 8 to 18 months. In contrast, ultrasound scanning was only able to detect one CBD stone, and there was a 14% incidence of inadequate visualisation of the CBD. Intravenous cholangiography is a safe, inexpensive, and highly accurate technique for assessing the CBD in patients undergoing laparoscopic cholecystectomy, with false-positive and false-negative rates of 0 in this study. The timing of the investigation permits preoperative clearance of the duct by ERCP and, should this fail, the option of a single procedure of open exploration of the CBD.

Adult↗
PubMed1993

Anoxia/reoxygenation induces hydroxyl free radical formation in brain microvessels.

Isolated rat brain microvessels have been utilized to examine whether they produce hydroxyl free radicals if they are subjected to a 10- to 20-min anoxia period followed by a 40-min reoxygenation period. Hydroxyl free radical flux was assessed utilizing salicylate as a trap. The 2,3- and 2,5-dihydroxybenzoic acids (DHBA) products as well as salicylate in the microvessels were quantitated utilizing high-pressure liquid chromatography (HPLC) with electrochemical and fluorescence detection. The results show that a period of anoxia followed by reoxygenation resulted in an enhanced formation of DHBA compared to the normoxic control microvessels. Addition of superoxide dismutase (SOD) and catalase to the microvessels undergoing anoxia decreased the amount of hydroxyl free radicals trapped, suggesting that superoxide and hydrogen peroxide were produced and excreted from the endothelial cell surfaces and then unless quenched reentered the cells to form hydroxyl free radicals within. The amount of 2,5-DHBA formed closely correlated with the amount of 2,3-DHBA formed, indicating that either product can be used to assess hydroxyl free radical flux in brain microvessels.

Animals↗
PubMed1993

Attended home titration of nasal continuous positive airway pressure therapy for obstructive sleep apnea.

Nasal continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea (OSA) is usually titrated in a sleep laboratory with full polysomnographic monitoring until apneas, nonapneic desaturation, snoring, and microarousals are eliminated. This titration is sometimes done in the second half of the diagnostic sleep study or commonly on a separate second full night in the sleep laboratory. We performed NCPAP titration in the home in 17 patients with OSA previously documented by full polysomnography. Nasal CPAP was titrated at night in the patient's home by a registered nurse or polysomnography technician monitoring real-time recordings of heart rate, thoracic impedance, oxygen saturation, and pressure at the nasal mask on a four-channel recorder (EdenTec, Eden Prairie, Minn). Recordings of the nasal CPAP titration night were reviewed later by a physician. Apneas, hypopneas, and snoring were successfully eliminated in all patients. Mean nasal CPAP pressure was 10.3 +/- 3.2 cm H2O. At the time of a follow-up interview, 13 of 17 patients continued to be compliant with nasal CPAP therapy. The mean duration of therapy was 13.4 +/- 11.7 months with 7.23 mean hours of use for 6.76 nights per week. This compliance compares favorably with long-term home nasal CPAP compliance previously reported in patients titrated in our sleep laboratory. Home nasal CPAP titration resulted in about a $600 savings per patient.

Home Care Services↗
PubMed1991

GAL4 is phosphorylated as a consequence of transcriptional activation.

GAL4 protein isolated from yeast in which it is active is phosphorylated predominantly on two different serine residues. One of these was identified as Ser-837; substitution of this residue for alanine has no detectable effect on transcriptional activation by GAL4. Phosphorylation at Ser-837 requires that both the DNA binding and transcriptional activation functions be intact. We propose that some phosphorylations of GAL4, including that at Ser-837, occur concomitantly with activation of transcription.

Amino Acid Sequence↗
PubMed1991

Generating yeast transcriptional activators containing no yeast protein sequences.

We previously reported that roughly 1% of the short peptides encoded by Escherichia coli genomic DNA fragments act as transcriptional activating regions in yeast when fused to GAL4(1-147), a DNA-binding portion of the yeast transcriptional activator GAL4 (ref. 1). Struhl questioned the conclusion that we had identified new transcriptional activating sequences that function in the absence of yeast transcriptional activating sequences. His criticism was based on two considerations: first, GAL4(1-147) contains an acidic segment (and subsequent experiments have shown that this region contains a weak activating region in vitro); second, attempts to isolate new activating regions failed when the DNA-binding domain of a bacterial repressor, LexA(1-87), was used as the DNA-binding unit. We report here a repeat of our original experiment using the complete LexA molecule LexA(1-202) as the DNA-binding region, instead of GAL4(1-147) or LexA(1-87). We find that, as in the original experiment, about 1% of the short peptides encoded by E. coli genomic fragments act as transcriptional activating regions when fused to intact LexA. All of the new activating regions whose sequences we determined bore an excess of acidic amino acids (see Table 1).

Amino Acid Sequence↗
PubMed1991

Comparative analysis of signaling pathways between mast cell growth factor (c-kit ligand) and granulocyte-macrophage colony-stimulating factor in a human factor-dependent myeloid cell line involves phosphorylation of Raf-1, GTPase-activating protein and mitogen-activated protein kinase.

Mast cell growth factor (MGF, the ligand for c-kit receptor) can stimulate proliferation of factor dependent myeloid cell line, M07e, and MGF synergizes with granulocyte-macrophage colony-stimulating factor (GM-CSF) or IL-3 in this effect. The effect of MGF on protein tyrosine kinase activity in M07e cells was investigated by immunoblotting with anti-phosphotyrosine mAb and this was compared with effects of GM-CSF. MGF stimulation rapidly induced or enhanced at least 12 tyrosine phosphorylated bands. Major bands had molecular weights of 145, 120, 110, 98, 62, 55 and 42 kD. P145, the most prominent phosphorylated protein, was identified as c-kit product using anti-c-kit-mAb (YB5.B8), suggesting ligand-dependent receptor autophosphorylation. Five of six tyrosine phosphorylated bands induced or enhanced by GM-CSF stimulation comigrated with those tyrosine phosphorylated by MGF (138, 120, 76, 55 and 42 kD). P42 was identified, at least in part, as mitogen-activated protein (MAP) kinase. MGF induced tyrosine phosphorylation of a complex of GTPase-activating protein (GAP, 120 kD) and GAP associated proteins (p62/p190) as detected by anti-GAP Ab immunoprecipitation followed by immunoblotting with anti-phosphotyrosine mAb. GM-CSF also stimulated slightly but consistently tyrosine phosphorylation of GAP and p190 but not p62. Both MGF and GM-CSF enhanced Raf-1 phosphorylation and increased Raf-1 associated kinase activity in vitro. Phosphoamino acid analysis revealed Raf-1 phosphorylation by these two growth factors occurred almost exclusively on serine residues. No tyrosine phosphorylation of Raf-1 protein was detected. These data suggest shared and unshared components of signaling pathways of both factors, which may be involved in cell proliferation.

Bone Marrow↗
PubMed1991

The six languages of social work.

This article describes the six languages that scientifically minded and practice-competent social workers need to be fluent in: the lay language of the client, the abstract language of the theorist, the empirical and often quantitative language of the researcher, the categorical language of the information scientist, the technical terminology or jargon used by helping professionals, and the preferential language that conveys values. It is the thesis of this article that social workers need multilingual and translingual proficiency in moving rapidly back and forth among these languages for maximum effectiveness and humane service.

Humans↗
PubMed1990

Mapping the cardiogenic impedance signal on the thoracic surface.

The cardiogenic impedance signal from band electrodes placed in the traditional position around the neck and lower thorax was studied by mapping the location of the signal on the sternum using 10 cm strip electrodes in eight male subjects. The band current electrodes on the neck and waist were replaced with 10 cm strip electrodes on the forehead and 10 cm below the xiphisternal joint, respectively, with only small changes in the dZ/dt peak amplitude and Z0. Similarly, using a strip voltage pickup electrode at the level of the xiphisternal joint resulted in very small changes in the waveform. The amplitude of dZ/dt measured between the xiphisternal joint and points along the sternum remains small until approximately 10 cm below the suprasternal notch, after which it increased linearly to the top of the neck. An average of 17 per cent and 24 per cent of the dZ/dt signal and 24 per cent and 22 per cent of the Z0 signal for supine and standing, respectively, occurs above the suprasternal notch. Replacing the current electrodes with strip electrodes on the forehead and waist caused only small changes in the signal. The position of the neck strip electrode is more critical.

Adult↗
PubMed1990

Abnormal eating attitudes in London schoolgirls--a prospective epidemiological study: outcome at twelve month follow-up.

The occurrence and course of eating disorder in a large representative population of 15-year-old London schoolgirls has been assessed using a two-stage survey methodology. Attempts to control weight were common and often transient. Dieting was in the great majority of girls found to be a benign practice without progression to more extreme concerns about food and weight. However, a small proportion of dieters did become cases and formed the majority of new cases found at follow-up. The relative risk of dieters becoming cases was eight times that of non-dieters. Many factors conventionally associated with eating disorder were associated more with attempting weight control than caseness. These included pre-morbid personality, pre-morbid obesity and family weight pathology. Other factors, including social class, career choice and psychosexual development, had no association either with attempting weight control or caseness.

Adolescent↗