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Biomedical subjects

C Walsh

Publications and source records attributed to C Walsh.

At least 145 records · Page 8Linked to original sources
PubMed1989

Vitamin K-dependent carboxylase: affinity purification from bovine liver by using a synthetic propeptide containing the gamma-carboxylation recognition site.

The vitamin K-dependent carboxylase catalyzes the posttranslational modification of specific glutamic acid residues to form gamma-carboxyglutamic acid residues within the vitamin K-dependent proteins. This enzyme recognizes the gamma-carboxylation recognition site on the propeptide of the precursor forms of the vitamin K-dependent blood coagulation proteins. To purify this enzyme to homogeneity, the carboxylase from bovine liver microsomes was solubilized with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), the protein was fractionated with ammonium sulfate, and then the enzyme was isolated by affinity chromatography using a synthetic peptide based upon the structure of the prothrombin propeptide. Elution with 10 mM propeptide yielded a single major band on SDS gel electrophoresis with a molecular weight of 77,000. In the presence of high concentrations of propeptide, only minimal carboxylase activity was measurable. Antibodies to the protein inhibited the carboxylase activity in crude preparations. In an alternative affinity purification strategy the propeptide was coupled through an NH2-terminal cysteine to an activated thiol-Sepharose column. The carboxylase-propeptide complex was eluted at 25 degrees C by reductive cleavage of the enzyme-propeptide complex in the presence of detergent and phospholipids. The eluted protein (Mr, 77,000) contained both stable vitamin K-dependent carboxylase and vitamin K epoxidase activity. The protein, purified by either method, was detected as a single band (Mr, 77,000) in a Western blot using anti-carboxylase antibodies. A 10,000-fold purification of carboxylase activity from crude microsomes was estimated. Purified bovine liver vitamin K-dependent carboxylase should facilitate the study of its structure and of the mechanism of action of vitamin K as a cofactor in the reaction catalyzed by this enzyme.

Amino Acid Sequence↗
PubMed1989

Rupture of the left ventricle and interventricular septum by blunt trauma.

We report a survivor of blunt trauma with rupture of the left ventricle and the interventricular septum. A review of the literature revealed no previous report of a survivor of this combination of nonpenetrating injuries, and only four previous survivors of left ventricular rupture due to blunt trauma.

Adult↗
PubMed1989

Nucleotide sequence of a chromosomal mercury resistance determinant from a Bacillus sp. with broad-spectrum mercury resistance.

A 13.5-kilobase HindIII fragment, bearing an intact mercury resistance (mer) operon, was isolated from chromosomal DNA of broad-spectrum mercury-resistant Bacillus sp. strain RC607 by using as a probe a clone containing the mercury reductase (merA) gene. The new clone, pYW33, expressed broad-spectrum mercury resistance both in Escherichia coli and in Bacillus subtilis, but only in B. subtilis was the mercuric reductase activity inducible. Sequencing of a 1.8-kilobase mercury hypersensitivity-producing fragment revealed four open reading frames (ORFs). ORF1 may code for a regulatory protein (MerR). ORF2 and ORF4 were associated with cellular transport function and the hypersensitivity phenotype. DNA fragments encompassing the merA and the merB genes were sequenced. The predicted Bacillus sp. strain RC607 MerA (mercuric reductase) and MerB (organomercurial lyase) were similar to those predicted from Staphylococcus aureus plasmid pI258 (67 and 73% amino acid identities, respectively); however, only 40% of the amino acid residues of RC607 MerA were identical to those of the mercuric reductase from gram-negative bacteria. A 69-kilodalton polypeptide was isolated and identified as the merA gene product by examination of its amino-terminal sequence.

Amino Acid Sequence↗
PubMed1989

When deaf people become elderly--counteracting a lifetime of difficulties.

1. Deaf people may feel like foreigners, alone and unable to relate with those in their environment. This is due to the lack of integration with and different enculturation than hearing persons. 2. Deaf individuals raised by hearing parents who cannot communicate with them may develop feelings of powerlessness and frustration. These feelings develop into doubt and distrust of all hearing people. 3. Deaf people feel more handicapped by hearing people's negative attitudes than by hearing loss itself. The elderly deaf people who perceive negative and discriminatory attitudes from hearing caregivers might be uncooperative or resentful. 4. The handicap of being deaf has a disabling effect beyond the hearing impairment and compound the effects of aging.

Aged↗
PubMed1989

Colony-stimulating factors in the treatment of HIV-associated non-Hodgkin's lymphoma.

Treatment results using standard chemotherapeutic regimens for patients with intermediate and high-grade non-Hodgkin's lymphoma have been disappointing. For patients with HIV-associated lymphoma, whose bone marrow tolerance is so limited, conservative dose combination chemotherapy has been the only realistic option. Now, however, the availability of recombinant colony-stimulating factors allows more dose-intensive therapy to be used. Both recombinant human granulocyte colony-stimulating factor and recombinant human granulocyte macrophage colony-stimulating factor have undergone Phase I testing and have been shown to reduce bone marrow toxicity following combination chemotherapy in non-HIV-infected patients. While this may be a promising lead for the treatment of HIV-infected patients also, it must be noted that until randomized trials are performed, no clear effects on survival or response can be verified.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Phase I study of the combination of alpha-2 interferon and cisplatinum.

Based on preclinical evidence of synergy, we performed a Phase I study of the combination of alpha-2 interferon and cisplatinum in patients with advanced malignancy. A fixed dose of 5 x 10(6) U/m2 alpha interferon was given three times weekly. Cisplatinum was given once weekly at dose levels of 5, 10, 20, 25, and 30 mg/m2. Dose-limiting toxicity consisted of flu-like symptoms and malaise leading to decreased performance status. Response was seen in a patient with metastatic melanoma. Recommended doses for Phase II study are 5 x 10(6) U/m2 of alpha-2 interferon three times weekly and 25 mg/m2 of cisplatinum once weekly.

Cisplatin↗
PubMed1988

Clonally related cortical cells show several migration patterns.

The mammalian cerebral cortex is organized into columns of cells with common functional properties. During embryogenesis, cortical neurons are formed deep, near the lateral ventricles, and migrate radially to their final position. This observation led to the suggestion that the cortex consists of radial, ontogenetic units of clonally related neurons. In the experiments reported here, this hypothesis was tested by studying cell lineage in the rat cortex with a retroviral vector carrying the Escherichia coli beta-galactosidase gene, which can be easily visualized. Labeled, clonally related cortical neurons did not occur in simple columnar arrays. Instead, clonally related neurons entered several different radial columns, apparently by migrating along different radial glial fibers.

Animals↗
PubMed1988

Cancer morbidity in lamp manufacturing workers.

A historical prospective study of cancer in lamp manufacturing workers in one plant was conducted. All men and women who worked for a total of at least 6 months and were employed at some time between 1960 and 1975 were included. Work histories were abstracted and subjects were divided according to whether they had worked in the coiling and wire drawing area (CWD). Cancer morbidity from 1964 to 1982 was ascertained via the provincial registry, and was compared with the site-specific incidence in Ontario, adjusting for age, sex and calendar period. Of particular interest were primary breast and gynecological cancers in women. The cancers of a priori concern were significantly increased in women in CWD, but not elsewhere in the plant. The excess was greatest in those with more than 5 yr exposure (in CWD) and more than 15 yr since first working in CWD, with eight cases of breast and gynecological cancers observed in this category compared with 2.67 expected. Only three cancers occurred in men in CWD. Environmental measurements had not been made in the past and little information was available on substances used in the 1940s and 1950s, the period when the women with the highest excess began employment. It is known that methylene chloride and trichlorethylene have been used, but not enough is known about the dates and patterns of use to draw any conclusions about their relationship with the increase in disease.

Breast Neoplasms↗
PubMed1988

Postoperative vomiting following strabismus surgery in paediatric outpatients: spontaneous versus controlled ventilation.

The study was designed to compare the frequency and severity of postoperative vomiting in paediatric out-patients receiving controlled ventilation (IPPV) or breathing spontaneously (SV) during anaesthesia for strabismus repair. One hundred and twenty unpremedicated children (ages 2-12 years) were studied in a randomized fashion. After intravenous induction of anaesthesia and tracheal intubation, patients breathed halothane 1-1.5 per cent inspired and N2O 66 per cent in O2 spontaneously (n = 60), or received IPPV, halothane 0.5-1 per cent, N2O 66 per cent, and pancuronium 0.05 mg.kg-1, which was reversed with neostigmine and atropine (n = 60). The incidence of vomiting with SV was 50 per cent (95 per cent confidence limits: 34.5-65.5 per cent) compared with 40 per cent (24.5-55.5 per cent) with IPPV (p greater than 0.25). Patients in the SV group experiencing emesis had longer operations than those not vomiting (mean +/- SEM = 1.5 +/- 0.1 vs 1.2 +/- 0.1 hours, p less than 0.005). This was not the case with IPPV. There was no correlation between age, sex, duration of surgery, or number of extraocular muscles repaired, and frequency or severity of vomiting or time to discharge. No significant advantage was afforded by IPPV over SV in the present study.

Child↗
PubMed1988

Contribution of SPECT to imaging of gastrointestinal adenocarcinoma with 111In-labeled anti-CEA monoclonal antibody.

Fourteen patients with suspected adenocarcinoma of the gastrointestinal tract received 1 mg of 111In-labeled anticarcinoembryonic antigen monoclonal antibody type ZCE025 combined with 40 mg unlabeled antibody of the same type. Planar and single-photon emission CT (SPECT) imaging studies were performed 3 days after infusion and, when possible, 7 days after infusion. Scan findings were correlated with the findings at surgery when possible. Tumor was detected by day-3 planar imaging in eight of 13 patients in whom tumor was documented histopathologically. Day-3 SPECT allowed demonstration of tumor in 11 of these 13 patients. In another patient whose scan was negative, no residual tumor was found at surgery. SPECT was particularly helpful in identifying small and midline tumors. In two cases, localization on SPECT helped identify the tumor mass on CT. Two primary tumors weighing less than 5 g could not be detected on either planar or SPECT scans. Histologically positive, normal-sized lymph nodes were not seen by planar imaging or SPECT. SPECT increased the detection rate over that achieved with planar imaging, helped to better localize scan abnormalities, and afforded more useful comparison between the monoclonal antibody study and CT.

Adenocarcinoma↗
PubMed1987

Changing glial organization relates to changing fiber order in the developing optic nerve of ferrets.

The structures of the developing eye-stalk and the relationships of early retinofugal fibers as they pass through the stalk, chiasm, and tract have been studied by light and electron microscopical methods in fetal ferrets aged 23-27 days. The early eye-stalk can be divided into two parts: a narrow extracranial part has a narrow lumen and is lined by few cells, whereas a thicker intracranial part has a wider lumen and is lined by several rows of cells. At the earliest stages no axon bundles are recognizable in the stalk, but fibers of the supraoptic commissure are already beginning to cross the midline in the diencephalon. Subsequently, as retinofugal axons invade the stalk, the glia of the extracranial part of the stalk have an interfascicular distribution and axon bundles are separately encircled by glial cytoplasm. In the intracranial part, as in the chiasm and tract, the glial cells occupy a periventricular position and send slender radial cytoplasmic processes to the subpial surface; these pass between groups of axons that here lie immediately deep to the subpial glia. Whereas axonal growth cones have no evident preferred distribution in the extracranial stalk, they tend to accumulate near the pial surface intracranially. The boundary between the two types of organization shifts as development proceeds so that the interfascicular glial structure of the early extracranial stalk first encroaches upon the intracranial parts and later appears in the chiasm. The characteristic adult arrangement of fibers in an age-related order in the optic chiasm and tract, but not in the optic nerve, can be understood if axonal growth cones are guided toward the pial surface by radial glia but not by interfascicular glia. From the distribution of the growth cones, this is what appears to happen.

Animals↗
PubMed1987

Early uncrossed component of the developing optic nerve with a short extracerebral course: a light and electron microscopic study of fetal ferrets.

During the study of the developing optic nerve described in the preceding paper (Guillery and Walsh, '87), small bundles of nerve fibers were seen passing between the optic nerve and the ipsilateral hypothalamus of 24-to 27-day-old prenatal ferrets. The bundles appear before any other fiber groups of the retinofugal pathway and are identifiable while the main portions of the retinofugal system are growing into the optic tracts. The bundles, made up of 50 or more axons, leave the optic nerve, emerge through the otherwise continuous layer of subpial glia and through the basal lamina of the nerve, run a short, naked, extracerebral course among collagen fibers and presumed fibroblasts, and then re-enter the central nervous system, passing rostrally and dorsally to the superficial parts of the ipsilateral hypothalamus away from the region of the chiasm. These fibers represent the earliest link between the optic nerve and the brain, but their course is not followed by the majority of retinofugal fibers developing later, which pass toward one or the other optic tract.

Animals↗
PubMed1987

Metalloregulatory DNA-binding protein encoded by the merR gene: isolation and characterization.

The MerR protein mediates the induction of the mercury resistance phenotype in bacteria; it has been isolated in order to study the effects of metal-ion induced changes in the metabolism of prokaryotic cells at the molecular level. After DNA sequences responsible for negative autoregulation were removed, the 16-kilodalton protein was overproduced and purified to more than 90 percent homogeneity by a salt extraction procedure that yields about 5 milligrams of protein per gram of cells. Complementation data, amino terminal analysis, gel filtration, and deoxyribonuclease I protection studies demonstrate that the purified merR gene product is a dimer under nondenaturing conditions and that it binds specifically to DNA, in the presence and absence of mercury, at a palindromic site which is directly between the -10 and -35 regions of the structural genes and adjacent to its own promoter. These initial results indicate that MerR is a DNA-binding metalloregulatory protein that plays a central role in this heavy metal responsive system and they delineate an operator site in the mer operon.

Amino Acid Sequence↗
PubMed1986

Mechanistic studies of the coenzyme F420 reducing formate dehydrogenase from Methanobacterium formicicum.

Mechanistic studies have been undertaken on the coenzyme F420 dependent formate dehydrogenase from Methanobacterium formicicum. The enzyme was specific for the si face hydride transfer to C5 of F420 and joins three other F420-recognizing methanogen enzymes in this stereospecificity, consistent perhaps with a common type of binding site for this 8-hydroxy-5-deazariboflavin. While catalysis probably occurs by hydride transfer from formate to the enzyme to generate an EH2 species and then by hydride transfer back out to F420, the formate-derived hydrogen exchanged with solvent protons before transfer back out to F420. The kinetics of hydride transfer from formate revealed that this step is not rate determining, which suggests that the rate-determining step is an internal electron transfer. The deflavo formate dehydrogenase was amenable to reconstitution with flavin analogues. The enzyme was sensitive to alterations in FAD structure in the 6-, 7-, and 8-loci of the benzenoid moiety in the isoalloxazine ring.

Aldehyde Oxidoreductases↗