Search PubMed⌕ Search

Biomedical subjects

C Cummings

Publications and source records attributed to C Cummings.

At least 19 recordsLinked to original sources
PubMed1996

A peroxovanadium compound induces Xenopus oocyte maturation: inhibition by a neutralizing anti-insulin receptor antibody.

Synthetic peroxovanadium compounds are a new class of potent inhibitors of protein phosphotyrosine phosphatases. These compounds exhibit insulin-like activity both in vitro and in experimental animals. However, the molecular mechanism by which these compounds exert their biological effect is not well defined. We demonstrate here that several of these compounds induce Xenopus oocyte maturation in vitro, as indicated by germinal vesicle breakdown. Using one of these compounds for further studies, we show that the induction is dose-dependent and is accompanied by activation of maturation promoting factor as well as activation of Xenopus MAP kinase. Like insulin, bpV(pic) causes an acute accumulation of PI(3,4,5)P3 (phosphotidylinositol-3,4,5-trisphosphate), a product of PI 3-kinase. More importantly, bpV(pic)-induced oocyte maturation was abolished by microinjection of a neutralizing monoclonal anti-insulin receptor antibody (17A3) into oocytes or preincubation of oocytes with a PI 3-kinase inhibitor (wortmannin). These results suggest that bpV(pic) acts upstream of the Xenopus IGF-1 receptor in the induction of meiotic maturation, presumably by neutralizing an inhibitory protein tyrosine phosphatase(s) that may regulate the receptor. Finally, using an oocyte-follicle cell complex that responded to human chorionic gonadotropin (hCG) to undergo GVBD, we showed that injection of 17A3 anti-insulin receptor antibody into oocytes did not affect hCG-induced oocyte maturation.

Androstadienes↗
PubMed1996

Secretion of Trichoderma reesei beta-glucosidase by Saccharomyces cerevisiae.

An intronless form of the bgl1 gene encoding an extracellular beta-glucosidase from Trichoderma reesei was expressed in the yeast Saccharomyces cerevisiae under the control of the yeast GAL1 promoter. Transformation of a yeast strain with this vector resulted in transformants that produce and secrete active beta-glucosidase into the growth medium. Additionally, active recombinant beta-glucosidase protein was shown to be localized predominantly in the periplasmic space by using a p-nitrophenyl beta-D-glycoside hydrolysis assay against fractionated yeast cells. The apparent size of the recombinant enzyme was 10-15 kDa larger than that of the native form. Treatment of the recombinant beta-glucosidase with endoglycosidase-H indicated the apparent increase in size was due to N-linked glycosylation.

Base Sequence↗
PubMed1996

Prevalence of anti-Rift-Valley-fever IgM antibody in abattoir workers in the Nile delta during the 1993 outbreak in Egypt.

In the early summer of 1993, an outbreak of Rift Valley fever (RVF) was reported among both humans and animals in Aswan Governorate, Upper Egypt. To determine whether RVF infection had spread to the Nile delta region of the country, we carried out a cross-sectional survey of 1181 occupationally exposed abattoir workers (97% male; age 10-72 years) in 15 governorates of Egypt in November 1993. The overall prevalence of anti-RVF virus IgM antibody was 2% (range: 0% (7 governorates) to 10%). The highest prevalences were in Ismailia (10%) and Sharqîya (8%) Governorates. None of the seropositive subjects reported having experienced an episode of fever in the 2 months prior to the study. The prevalence of antibody was significantly higher (P < 0.05) among workers employed in high-risk jobs such as cutting animals' throats (relative risk (RR = 2.24)) and handling animal parts (RR = 2.37). The findings suggest that abattoir workers represent a useful sentinel population for surveillance of RVF.

Abattoirs↗
PubMed1996

The views of general practitioners on community carrier screening for cystic fibrosis.

BACKGROUND: Recent developments in molecular genetics have made it possible to identify carriers of the cystic fibrosis (CF) mutation, regardless of family history, before they have an affected child. Using these techniques, population or 'community' carrier screening can offer informed reproductive choice to individuals and couples who would not otherwise know of their risk of having a CF child. AIM: This study set out to assess the views of general practitioners (GPs) on community carrier screening for CF and to consider the factors that influence their willingness to offer it themselves. METHOD: A self-administered questionnaires was sent to all 616 GPs in four areas of North Thames (West) Region. RESULTS: Two-thirds of respondents indicated that identifying carrier couples to offer genetic counselling before conception was a very important benefit of community carrier screening. Two-thirds felt that general practice was the most appropriate place in which to offer it, and similar proportions that the most appropriate times to do so were when a close relative was diagnosed and when seeking family planning. About half wanted to offer community carrier screening themselves; this was related to experience with CF patients and CF carrier testing, and estimates of the numbers of CF carriers in the practice. CONCLUSIONS: There is considerable support among GPs for community carrier screening for CF in general practice, particularly in the context of family planning services. Knowledge and experience of CF increase GPs' willingness to offer it themselves.

Attitude of Health Personnel↗
PubMed1996

Isolation of Campylobacter species from Zambian patients with acute diarrhoea.

Four hundred and one consecutive diarrhoea patients and 101 adult patients without diarrhoea were enrolled for this study from a health centre in Lusaka. Campylobacter was isolated from 6% of patients with acute diarrhoea. However, non of these were seen in control group. Further studies are being carried out to determine the importance of Campylobacter species with other bacterial pathogens. It will also be interesting to see its impact and association with human immuno deficiency virus in this region.

Acute Disease↗
PubMed1994

Total quality management and shared governance: synergistic processes.

"Synergism" accurately describes the gains that can be made when total quality management (TQM) and shared governance are employed for reciprocal development. This article explores the relationship between TQM and shared governance from a systems perspective. Systems thinking is the fundamental framework that must be learned by nursing managers. An example of this synergistic process is described from the National Institutes of Health nursing department's experience in implementing TQM and shared governance. The idea that structure is fundamental to problems and solutions when implementing change and focusing upon interdependency issues are the systemic competencies nursing managers need to develop in order to become strong nursing leaders.

Decision Making, Organizational↗
PubMed1994

Inhibition of Na+/Ca2+ exchange in renal BLMV by IP3 depends on site of action and direction of Ca2+ flux.

It has previously been shown in synaptosomes that inositol 1,4,5-trisphosphate (1,4,5-IP3) inhibits Ca2+ transport by the plasma membrane-bound Na+/Ca2+ exchanger. The present study was therefore designed to determine if the effect of 1,4,5-IP3 was dependent on its site of action at the plasma membrane or on the direction of Ca2+ flux. To investigate this possibility, studies were performed in basolateral membrane vesicles (BLMV) isolated from rat renal cortex. As with synaptosomes, Ca2+ transport was inhibited by 1,4,5-IP3 in a concentration-dependent manner. At a concentration of 10(-6) M, 1,4,5-IP3 significantly (P < 0.005) inhibited Ca2+ transport by 36%. When Ca2+ transport was carried out in inside-out vesicles, 10(-6) M 1,4,5-IP3 significantly (P < 0.002) increased the degree of inhibition by an additional 75% (63 vs. 36%). However, 1,4,5-IP3 had no significant effect on Ca2+ transport in inside-out vesicles when Ca2+ flux was reversed (i.e., Ca2+ efflux). These data in renal BLMV confirm the novel action of 1,4,5-IP3 on the Na+/Ca2+ exchanger previously described in brain synaptosomes. These results also suggest that the action of 1,4,5-IP3 depends on both its site of action at the plasma membrane and on the direction of Ca2+ flux.

Analysis of Variance↗
PubMed1993

Isolation of a novel 45 kDa plasminogen receptor from human endothelial cells.

We have previously identified an endothelial cell membrane protein of M(r) 45 kDa that binds plasminogen in a kringle-dependent, specific and reversible manner (Dudani et. al. (1991) Mol. Cell. Biochem. 108: 133-139). In this study, we have developed and optimized a protocol for the isolation of the 45 kDa plasminogen receptor from venous endothelial cells using a four step procedure consisting of lysis and detergent extraction followed by ligand affinity chromatography and preparative polyacrylamide gel electrophoresis. Control experiments were carried out using BSA-Sepharose instead of plasminogen-Sepharose as the affinity matrix. No plasminogen binding proteins were recovered from the former columns. However, a 45 kDa protein was recovered from lysine eluates of plasminogen-Sepharose. This material was then purified to homogeneity using preoperative electrophoresis. Analyses of proteins at various steps in the purification by SDS-PAGE showed enrichment of a band of 45 kDa which superimposed with the observed binding activity of plasminogen in ligand blots. The above binding could be inhibited by excess lysine. The 45 kDa protein could be distinguished from alpha-enolase which also binds plasminogen by: (i) significant differences in the profile of retention times of CNBr-degradation fragments on reversed phase HPLC; and (ii) partial peptide sequencing of one of the CNBr-degradation fragments of the 45 kDa protein. Moreover, the derived sequence did not show any significant homology to any protein in the Swiss Prot (release 20) database. We thus propose that the 45 kDa protein represents a novel plasminogen receptor on human venous endothelial cells.

Amino Acid Sequence↗
PubMed1993

Recovery after allogeneic marrow transplantation: prospective study of predictors of long-term physical and psychosocial functioning.

No prospective data have documented the physical and psychosocial functioning of patients before and after BMT. In this study 67 allogeneic transplant patients completed standardized self-report measures pre-transplant. Survivors were re-assessed at 90 days (n = 34) and 1 year (n = 31) post-transplant. Telephone interviews established 4-year work history and performance status. Physical function was most impaired at 90 days post-transplant, with a return to pre-transplant levels of functioning by 1 year in most areas. By 2 years post-transplant, 68% of patients had returned to full-time work. Only 9% of 4-year survivors failed to return to full-time occupations. Mean levels of anxiety and depression did not change over the first year. Pre-transplant, 27% of patients reported depression and 41% reported elevated anxiety. Greater emotional distress at 1 year was predicted by pre-transplant family conflict, non-married status and development of less severe chronic GVHD. Impaired physical recovery at 1 year was predicted by more severe chronic GVHD, pre-transplant physical impairment and family conflict. The large majority of long-term survivors returned to full-time employment with normal physical and psychosocial functioning, although recovery took longer than 1 year for approximately 40%. Family relationships were important determinants of physical and emotional recovery.

Adult↗
PubMed1991

Secondary and tertiary structures of hyaluronan in aqueous solution, investigated by rotary shadowing-electron microscopy and computer simulation. Hyaluronan is a very efficient network-forming polymer.

1. Hyaluronan from mesothelioma fluid, rooster comb and streptococci was examined by rotary shadowing and electron microscopy. All preparations showed extensive branched networks, but high-viscosity hyaluronan networks were essentially infinite, with no individual 'molecules' that were not integrated via multiple branched points into the meshwork. Low-viscosity hyaluronan, recovered after papain digestion of mesothelioma fluid, showed occasional single filaments that were independent of the main aggregates, some of which were themselves independent of other aggregates. 2. Hyaluronan is a polymer with a very marked capability to form meshworks at very low dilution (less than 1 microgram/ml). The longer the hyaluronan molecule, the more branching is potentially possible, and the more extensive and coherent is the network, with every hyaluronan molecule in contact with every other in the solution, via the network. This behaviour accounts for the mechanical properties of the soft tissues (e.g. vitreous humour) and fluids (e.g. synovial fluid) of which hyaluronan is a major component. 3. The hyaluronan twofold helix, previously demonstrated to be present in solution [Heatley & Scott (1988) Biochem. J. 254, 489-493] was shown by computer simulation and energy calculations to be sterically capable of extensive duplex formation, probably driven by interactions between the large hydrophobic patches on alternate sides of the tape-like polymer, forming stable aggregates at biological temperatures in water. This 'stickiness' is postulated to be the basis of the network-forming and laterally aggregating behaviour of hyaluronan. 4. The tertiary structures formed by hyaluronan may not be possible in the case of chondroitin 4-sulphate.

Animals↗
PubMed1991

Isolation and ultrastructural analysis of microfibrillar structures from foetal bovine elastic tissues. Relative abundance and supramolecular architecture of type VI collagen assemblies and fibrillin.

Extensive intact assemblies of matrix macromolecules have been solubilized from foetal calf skin, nuchal ligament and aorta by a new procedure that includes bacterial collagenase digestion under non-reducing, non-denaturing conditions and gel filtration chromatography. Type VI collagen was identified as the major microfibrillar element of these tissues by SDS-PAGE analysis and Western blotting. Rotary shadowing electron microscopy of these preparations revealed by far the most abundant and extensive arrays of intact collagen VI microfibrils isolated to date. The distinct microfibrillar species, fibrillin, which was identified on the basis of its periodicity and morphology, was also solubilized in abundance by this protocol. Analysis of these complex polymers has generated new information on their supramolecular architecture and relative abundance in these tissues. The protocol also demonstrates that the release of intact collagen VI microfibrils from these tissues is largely dependent on the removal of the major collagen fibrils.

Animals↗
PubMed1990

D-periodic assemblies of type I procollagen.

The solubility limit of purified chick type I procollagen, incubated at 37 degrees C in phosphate-buffered saline, was found to be in the range 1 to 1.5 mg/ml. At higher concentrations large aggregates formed. These comprised: (1) D-periodic assemblies; (2) narrow filaments with no apparent periodicity; and (3) segment-long-spacing-like aggregates. The D-periodic assemblies, which predominated at high concentrations, were separated from the other types of aggregate and found to be ribbon-like. Ribbons were uniform in thickness (approximately 8 nm) and up to 1 micron wide. Staining patterns showed features similar to those in native-type collagen fibrils. Immunolabelling indicated that the carboxyl-terminal propeptide domains were close to the carboxyl-terminal gap-overlap junction, and that the amino-terminal propeptide domains were folded over into the amino-terminal side of the overlap zone. Both propeptide domains appeared to be located on the surface of the assemblies. These observations show that intact propeptide domains hinder, but do not prevent, the formation of D-periodic assemblies. The presence of the propeptide domains on the surface of a growing assembly could restrict its lateral growth and limit its final thickness.

Animals↗
PubMed1990

Examination of corneal proteoglycans and glycosaminoglycans by rotary shadowing and electron microscopy.

Proteoglycans (PGs) from cornea and their relevant glycosaminoglycan (GAG) chains, dermatan sulphate (DS) and keratin sulphate (KS), were examined by electron microscopy following rotary shadowing, and compared with hyaluronan (HA), chondroitin sulphate (CS), alginate, heparin, heparan sulphate (HS) and methyl cellulose. Corneal DS PG had the tadpole shape previously seen in scleral DS FG, and the images from corneal KS PG could be interpreted similarly, although the GAG (KS) chains were very much fainter than those of DS PG GAG. Isolated GAG (KS, DS, CS, HA, etc.) examined in the same way showed images that decreased very significantly in clarity and contrast, in the sequence HA greater than DS greater than CS greater than KS. The presence of secondary and tertiary structures in the GAGs may be at least partly responsible for these variations. HA appeared to be double stranded, and DS frequently self-aggregated, KS and HS showed tendencies to coil into globular shapes. It is concluded that it is unsafe to assume the absence of GAGs, based on these techniques, and quantitative measurements of length may be subject to error. The results on corneal DS PG confirm and extend the hypothesis that PGs specifically associated with collagen fibrils are tadpole shaped.

Alginates↗
PubMed1989

Pleomorphism in type I collagen fibrils produced by persistence of the procollagen N-propeptide.

The assembly of type I collagen and type I pN-collagen was studied in vitro using a system for generating these molecules enzymatically from their immediate biosynthetic precursors. Collagen generated by C-proteinase digestion of pC-collagen formed D-periodically banded fibrils that were essentially cylindrical (i.e. circular in cross-section). In contrast, pN-collagen generated by C-proteinase digestion of procollagen formed thin, sheet-like structures that were axially D-periodic in longitudinal section, of varying lateral widths (up to several microns) and uniform in thickness (approximately 8 nm). Mixtures of collagen and pN-collagen assembled to form a variety of pleomorphic fibrils. With increasing pN-collagen content, fibril cross-sections were progressively distorted from circular to lobulated to thin and branched structures. Some of these structures were similar to fibrils observed in certain heritable disorders of connective tissue where N-terminal procollagen processing is defective. The observations are considered in terms of the hypothesis that the N-propeptides are preferentially located on the surface of a growing assembly. The implications for normal diameter control of collagen fibrils in vivo are discussed.

Collagen↗
PubMed1989

Efficacy of neonatal ocular prophylaxis for the prevention of chlamydial and gonococcal conjunctivitis.

Opinions differ concerning the efficacy of prophylaxis against neonatal chlamydial and gonococcal conjunctivitis. From January 1986 through June 1988, we gave all infants born at Kings County Hospital Medical Center one of three prophylactic agents -- silver nitrate drops, erythromycin ophthalmic ointment, or tetracycline ophthalmic ointment. The treatments were rotated monthly. Gonococcal ophthalmia occurred in 8 of the 12,431 infants born during the study (0.06 percent), 1 in the silver nitrate group, 4 in the erythromycin group, and 3 in the tetracycline group (P not significant). Seven of these infants were born to women who had received no prenatal care. From September 1985 through December 1987, we screened 4357 pregnant women for cervical chlamydial infection, of whom 341 (8 percent) had positive cultures. Of their offspring, 230 were evaluated for neonatal chlamydial conjunctivitis; the incidence was 20 percent in the silver nitrate group, 14 percent in the erythromycin group, and 11 percent in the tetracycline group (P not significant). We conclude that neonatal ocular prophylaxis with either erythromycin or tetracycline ophthalmic ointment does not significantly reduce the incidence of chlamydial conjunctivitis in the offspring of mothers with chlamydial infection as compared with silver nitrate, and that better management of maternal chlamydial infection is therefore required. We also conclude that there is a small but appreciable incidence of neonatal gonococcal ophthalmia that could be prevented by better prenatal screening and treatment of maternal gonococcal infection.

Chlamydia Infections↗
PubMed1989

A model for ambulatory care of patients with epilepsy and other neurological disorders.

A model for ambulatory care of patients with epilepsy and other neurological disorders facilitates delivery of high quality nursing care, provides a framework for formulating standard nursing care plans and incorporates patient education components. Education and development of nurses working in this setting is fostered through caregiving activities and development of teaching materials coordinated through the model. The model can be modified to meet the needs of each patient or the requirements of various clinical research protocols and adapted to patients with non-neurological medical or surgical diagnoses.

Ambulatory Care↗