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Biomedical subjects

C Carter

Publications and source records attributed to C Carter.

At least 235 records · Page 13Linked to original sources
PubMed1981

Gene segments encoding transmembrane carboxyl termini of immunoglobulin gamma chains.

In cell lines producing IgM, secreted and membrane bound forms of immunoglobulin mu heavy chains are produced from two separate mu mRNAs that are identical except for alternative 3' coding sequences. We now show that cell lines producing IgG likewise contain two mRNA species for immunoglobulin gamma chains. The major, 1.7 kilobase (kb) species encodes secreted gamma chains. A less abundant species of 3-4 appears to encode membrane bound gamma chains, in that it contains an alternative 3' end encoded in separate exons 3' to the remainder of the gene. The first exon of this M gene segment has been identified in chromosomal gamma 1 and gamma 2b gene clones by its sequence homology with the corresponding exon in the mu gene. Like the mu M exon, it encodes a probable transmembrane polypeptide segment. The flanking DNA sequences show a patchwork pattern of homology between genes that suggests a checkered evolutionary history.

Amino Acid Sequence↗
PubMed1981

Reduction of Hydraulic Conductivity during Inhibition of Exudation from Excised Maize and Barley Roots.

The uncoupler, carbonyl cyanide m-chlorophenyl hydrazone (CCCP) is shown to reduce the hydraulic conductivity of barley, maize, mung bean, and onion roots. In barley and maize, the reduction in exudation from excised roots is partly due to the reduction in the permeability of the root to water (I(p)), but it can be inferred that the rate of salt release to the xylem, is also inhibited. The action of CCCP on L(p) is suggested to be mainly in blocking the symplasmic pathway at the plasmodesmata.

Journal Article↗
PubMed1981

Experimental ulcerative herpetic keratitis. I. Systemic immune responses and resistance to corneal infection.

The influence of previous infection with herpes simplex virus (HSV) on the susceptibility of rabbits to corneal inoculation of the virus was studied by means of the microtitration model for ulcerative herpetic keratitis. Systemic immune responses were assayed after skin and eye infections by means of the lymphocyte transformation (LT) and complement fixation (CF) tests. Both cutaneous and ocular primary infections resulted in cellular and humoral immune responses to HSV. In comparison to primary ocular infection, corneal disease in rabbits with previous skin infection ('secondary corneal infection') resulted in earlier initiation of cellular and humoral immune responses, while complement-fixing antibody titres reached a higher level. A previous cutaneous infection ('immunisation') provided considerable protection to the cornea and also accelerated recovery from corneal ulcerative disease. A correlation was observed between the initiation of the lymphocyte transformation response and the beginning of healing of corneal ulceration. A previous unilateral ocular infection induced an even higher degree of corneal resistance in that eye, and the opposite eye was protected to the same extent as by cutaneous immunisation.

Animals↗
PubMed1981

Systemic immunity in herpetic keratitis.

The importance of specific immunity, especially cell-mediated, in resistance to herpes simplex disease is well documented, and animal experiments show that immune responses to previous herpetic infection can give considerable protection against reinfection in epithelial keratitis. Since susceptibility to stromal herpetic keratitis is probably determined in part by the extent of virus proliferation in the epithelium, immune responses to herpes simplex virus were studied in patients with epithelial or stromal keratitis, a group of patients with keratitis who were also severely atopic, and controls. The parameters measured were lymphocyte transformation, production of macrophage migration inhibition factor, and levels of serum antibody and immunoglobulin. No group differences were found except for a slight decrease in the whole blood culture assessment of lymphocyte transformation in stromal keratitis patients compared with seropositive controls and patients with epithelial disease. It is considered that in a small group of patients a deficiency in the specific cell-mediated immune response plays a role in determining the spread of virus into the corneal stroma.

Adolescent↗
PubMed1981

Clinical validity of a negative venogram in patients with clinically suspected venous thrombosis.

Although it is generally accepted that negative venography excludes deep vein thrombosis (DVT) in patients in whom it is clinically suspected, there is no evidence to support this conclusion. To test the correctness of withholding anticoagulant therapy in these patients, we followed 160 consecutive patients who had clinically suspected DVT and negative venograms to determine the frequency of postvenographic DVT. Anticoagulant therapy was withheld in all patients. No patient died or developed pulmonary embolism during 3 months of follow-up. Two of the 160 patients (1.3%) attended the clinic on an emergency basis during follow-up with new symptoms of DVT and in both patients, DVT was confirmed by objective testing. These events developed within 5 days of venography, which suggests that they were induced by venography. Nevertheless, the findings indicate it is safe to withhold treatment in patients with clinically suspected DVT and negative venograms.

Adolescent↗
PubMed1981

Replacement of venography in suspected venous thrombosis by impedance plethysmography and 125I-fibrinogen leg scanning: a less invasive approach.

Noninvasive diagnostic testing is gaining acceptance in the evaluation of patients with clinically suspected venous thrombosis. Although clinically useful, all these tests have limitations, and the safety of basing therapeutic decisions on their outcome has not been assessed. We have done a prospective study of 322 symptomatic patients to ascertain the safety of replacing venography with impedance plethysmography and leg scanning. To provide a diagnostic reference, we did venography in all patients but withheld anticoagulants if the noninvasive tests were negative irrespective of the results of venography. None of the 163 patients with negative noninvasive tests died or developed clinical pulmonary embolism during 3 months' follow-up, confirming the safety of this approach. In two, clinically evident postvenographic venous thrombosis developed, confirmed by repetition of these objective tests. Also, the positive predictive values indicate that therapeutic decisions can be based on a positive noninvasive outcome in patients without clinical disorders known to produce false-positive results.

Adolescent↗
PubMed1980

Two mRNAs with different 3' ends encode membrane-bound and secreted forms of immunoglobulin mu chain.

During differentiation, B lymphocytes undergo a shift from expression of membrane-bound IgM to IgM secretion. The mu chains of membrane and secreted IgM, mum and mus, respectively, differ in the amino acid sequence of their carboxy terminal regions. In this paper, we demonstrate that mum and mus heavy chains are encoded by separate mRNAs of 2.7 and 2.4 kb, respectively. Restriction mapping and sequence analysis of mu cDNA clones from a myeloma tumor that produces both types of mu chain indicate that the mum and mus mRNAs are identical throughout the coding region up to the 3' end of the fourth constant region (Cmu 4) domain, but differ in their C terminal coding and 3' untranslated segments. From the nucleotide sequence of the mum cDNA clone, we predict the amino acid sequence of the 41-residue mum C terminal segment or "M" (membrane) segment. This sequence has characteristics consistent with its being a transmembrane peptide. Thus the mus chain has a 20-residue hydrophilic C terminal segment after the Cmu 4 domain, and the mum chain has a 41-residue C terminal segment containing a hydrophobic sequence. We propose that comparable C terminal segments also will be found in other membrane-bound immunoglobulin heavy chains.

Animals↗
PubMed1980

Inhibition of concanavalin A-induced human lymphocyte mitogenic factor (Interleukin-2) production by suppressor T lymphocytes.

Supernatants of fresh human MNL stimulated with concanavalin A (Con A) generally contain little or no lymphocyte-derived mitogenic factor (LMF or Interleukin-2). However, preincubation of MNL in culture medium for 2 to 5 days before stimulation with Con A rendered them capable of producing increasing LMF. The production of LMF by reincubated MNL was inhibited by readdition of autologous fresh MNL or E-rosetting (T) lymphocytes. The producing cells were T lymphocytes; however, the production of LMF was monocyte dependent. LMF eluted from a Sephadex G150 column in 2 peaks at 12 to 27,000 and 50 to 70,000 daltons. Both species of LMF were mitogenic for mouse (C3H/HeJ) thymocytes and for human T and B cells. LMF production was not affected by x-irradiation (less than or equal to 2500 R) before preincubation; it was, however, abolished by the addition of 10(-7) M hydrocortisone during the preincubation period. LMF production by fresh MNL could be moderately enhanced by the addition of cimetidine, a drug that is known to interfere with histamine H2 receptors on suppressor T cells. Presumably, preincubation of MNL reduces the activity of Con A-induced suppressor cells. We conclude that human peripheral blood contains suppressor T cells that when activated by Con A regulate the production of LMF by other T cells in response to Con A.

Cell Adhesion↗
PubMed1979

SHUR: a shift of power?

HEW's Health Care Financing Administration links uniform reporting and Medicare reimbursement under the provisions of the proposed System for Hospital Uniform Reporting. This summary of a position paper published by the public accounting firm Ernst & Ernst covers two questions: What will SHUR mean to hospitals? and, What can be done about it?

Accounting↗
PubMed1979

Mechanisms of resistance and hypersensitivity in herpes simplex keratitis.

Laboratory studies show that systemic immunity protects the corneal epithelium against herpes simplex virus (HSV) infection, this protection probably being humoral in origin. It can be shown that hyperimmune gammaglobulin (HGG) has a similar protective action when instilled up to 2 hours after the induction of the ulcerative disease. Topical steroids enhance proliferation of HSV in epithelial disease, but at low dilutions there is some evidence that resistance is enhanced. Human studies of systemic immunity show that there is a response in cell-mediated immunity (CMI) after primary and recurrent ulcerative disease. Certain patients with severe stromal keratitis have evidence of CMI deficiency compared to controls or to patients with epithelial disease. To prevent virus spread into the stroma, early use of antiviral therapy is essential. Stromal disease does not only represent a hypersensitivity phenomenon, but is probably associated with virus proliferation in the keratocytes. Potent steroid medication will theoretically deplete immuno-protective responses, and promote further virus proliferation. Therefore the lowest possible concentrations achieving a clinical response should be employed.

Adrenal Cortex Hormones↗
PubMed1978

Systemic immunosuppression in marginal keratolysis.

Experience in the investigation and treatment of eleven patients with the peripheral corneal melting syndrome is described. It is considered that short-term treatment with non-corticosteroid immunosuppressive regimes should be tried in patients with severe progressive disease which may not respond to other methods of treatment.

Aged↗
PubMed1977

Effect of polychlorinated biphenyl (PCB) on the thyroid gland of rats. Ultrastructural and biochemical investigations.

Polychlorinated biphenyls (PCB) produced ultrastructural lesions in thyroid follicular cells and reductions in serum thyroxine levels in rats that were time- and dose-dependent. The acute effects (4 week) of PCB (50 and 500 ppm) consisted of an accumulation of lysosomal bodies and colloid droplets in follicular cells with abnormalities of microvilli on the luminal surface. The chronic administration (12 week) of PCB (50 and 500/250 ppm) resulted in a striking distention of many follicular cells with large lysosomal bodies with strong acid phosphatase activity and colloid droplets, blunt and abnormally branched microvilli, and mitochondrial vacuolation. These ultrastructural alterations in follicular cells were associated with a highly significant reduction in serum thyroxine with both the low and the high dose of PCB. Follicular cells remained responsive to the lowered thyroxine level after feeding PCB for 4 and 12 weeks and underwent moderate compensatory hypertrophy and hyperplasia. Thyroid follicles were smaller than in controls and were lined by more columnar cells that occasionally formed papillary projections into the colloid. Residual ultrastructural alterations persisted for 12 weeks following cessation of feeding the compound, and serum thyroxine levels were significantly lower than in control rats. However, 35 weeks after discontinuing PCB, thyroid follicular cells were similar to those in controls and serum thyroxine levels had returned to normal. The striking ultrastructural lesions in follicular cells produced by feeding PCB to rats appeared to contribute to the lowering of serum thyroxine levels, in combination with the known stimulation of peripheral thyroxine metabolism by these compounds. Certain metabolic alterations produced by PCB intoxication in experimental animals and human beings may be related to an alteration in thyroid function.

Animals↗