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Biomedical subjects

C L Day

Publications and source records attributed to C L Day.

At least 19 recordsLinked to original sources
PubMed1994

Three-dimensional structure of lactoferrin in various functional states.

The three-dimensional structures of various forms of lactoferrin, determined by high resolution crystallographic studies, have been compared in order to determine the relationship between structure and biological function. These comparisons include human apo and diferric lactoferrins, metal and anion substituted lactoferrins, the N-terminal half molecule of human lactoferrin, and bovine diferric lactoferrin. The structures themselves define the nature and location of the iron binding sites and allow anti-bacterial and putative receptor-binding regions to be mapped on to the molecular surface. The structural comparisons show that small internal adjustments can allow the accommodation of different metals and anions without altering the overall molecular structure, whereas large-scale conformational changes are associated with metal binding and release, and smaller, but significant, movements accompany species variations. The results also focus on differences in flexibility between the two lobes, and on the importance of interactions in the inter-lobe region in modulating iron release from the N-lobe and in possibly enabling binding at one site to be signalled to the other.

Animals↗
PubMed1994

Lactoferrin cDNA. Expression and in vitro mutagenesis.

The full length copy DNA (cDNA) for human lactoferrin has been synthesised by the polymerase chain reaction (PCR) using sequence specific primers. The template was first strand cDNA, synthesised from human bone marrow RNA using oligo(dT) to prime DNA synthesis by MMLV reverse transcriptase. The full-length human lactoferrin cDNA has been expressed in baby hamster kidney (BHK) cells using the expression vector pNUT. The protein expressed from the cloned cDNA is secreted into the culture medium and yields of up to 40 mg per litre have been obtained. A mutant protein corresponding to the N-lobe of human lactoferrin (LfN) has also been expressed in BHK cells. The cDNA coding for this protein was produced by the introduction of stop codons into the region of the cDNA corresponding to the helix linking the N- and C-lobes of the native protein. LfN is also expressed as a secreted protein and has been obtained in high yield. LfN binds iron and has UV/Vis and ESR spectra which are virtually identical to the native protein. However, the pH at which iron is released from LfN is quite different to the pH of iron release from the native and the full-length recombinant protein. A number of mutations have been introduced into LfN by site-directed mutagenesis and the mutant proteins expressed in BHK cells. These mutations involve the iron binding ligands and have been designed to introduce some of the changes found in the C-lobe of melanotransferrin into LfN. An attempt has been made to express a protein corresponding to the C-lobe of human lactoferrin (LfC) by attaching the sequence for the signal peptide of lactoferrin to the cDNA sequences coding for the C-lobe.

Amino Acid Sequence↗
PubMed1993

Structure of the recombinant N-terminal lobe of human lactoferrin at 2.0 A resolution.

The three-dimensional structure of the N-terminal half-molecule of human lactoferrin, LfN, prepared by recombinant DNA methods, has been determined by X-ray crystallography at 2.0 A resolution. The protein is in its iron-bound form and is deglycosylated. X-ray diffraction data were obtained by diffractometry to 3.2 A resolution and synchrotron data collection, using Weissenberg photography with imaging plates, to 1.8 A resolution. The structure was solved by molecular replacement, using the N-lobe of native diferric human lactoferrin (Lf) as search model. Restrained least squares refinement (program TNT) has resulted in a model structure with an R-factor of 0.184 for all data 34,180 (reflections) in the resolution range 8.0 to 2.0 A. The model comprises 2490 protein atoms (residues 4 to 327), 1 Fe3+, 1 CO3(2-) and 180 solvent molecules, all regarded as water. The structure of LfN is essentially the same as that of the N-lobe of intact Lf, being folded into two similar alpha/beta domains, with the Fe3+ and CO3(2-) bound in a specific site in the interdomain cleft. These details are not affected by either deglycosylation or expression in a non-native system. At the C terminus, however, the conformation of residues 321 to 333 is changed. Whereas in Lf residues 321 to 332 form a helix crossing between the domains at the back of the iron site, in LfN residues 321 to 326 have an extended conformation, forming a third interdomain beta-strand, and residues 328 to 333 appear disordered. The conformational change is attributed to the loss of stabilizing interactions from the C-lobe and is mediated by two Gly residues, at positions 321 and 323. It is further proposed that the conformational change is responsible for the more facile iron release properties of LfN, by its effect on the hinge mechanism and increased solvent exposure of residues near the back of the iron site. Other details of the polypeptide chain conformation and the binding site have also been analysed. Two cis-proline residues are found at positions 71 and 142. The bidentate binding of the CO3(2-) to the metal ion is unambiguous, and a network of hydrogen bonds in and around the binding site links the two domains. Clearly-defined amino-aromatic hydrogen bonds are found for Arg210, near the metal site, and some 31 internal water molecules have been identified, 15 of them in essentially discrete sites, and 16 in a cluster filling a cavity in the interdomain cleft.

Anions↗
PubMed1992

Preliminary crystallographic studies of the amino terminal half of human lactoferrin in its iron-saturated and iron-free forms.

The amino terminal half of human lactoferrin (LfN) produced from transfected baby hamster kidney cells has been crystallized in its iron-saturated and iron-free forms. The crystals of glycosylated LfN and deglycosylated LfN are monoclinic, space group C2, with cell dimensions a = 133.0 A, b = 58.3 A, c = 58.3 A, alpha = 90.0 degrees, beta = 114.7 degrees, gamma = 90.0 degrees, and one molecule per asymmetric unit. Crystals of apo LfN have also been prepared using deglycosylated protein. These crystals are tetragonal, space group P4(1)2(1)2 (or P4(3)2(1)2), with cell dimensions of a = b = 58.4 A and c = 217.2 A and one molecule per asymmetric unit. Both the iron-saturated and the iron-free crystals are suitable for high resolution X-ray analysis.

Apoproteins↗
PubMed1992

Studies of the N-terminal half of human lactoferrin produced from the cloned cDNA demonstrate that interlobe interactions modulate iron release.

The factors influencing iron binding and release by lactoferrin have been addressed by comparison of the native full length molecule (Lf) with the N-terminal half of human lactoferrin (LfN) produced from the cloned cDNA expressed in baby hamster kidney (BHK) cells. The coding sequences for LfN were inserted into the expression vector pNUT between the metallothionein promoter and the human growth hormone transcription termination sequences. Transformed BHK cells were grown in roller bottles where concentrations of LfN as high as 35 mg/liter were obtained. The pure protein, produced by the transformed BHK cells, was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, protein blotting and immunodetection, N-terminal sequence analysis, UV-visible spectroscopy, electron spin resonance spectroscopy, and measurements of metal binding and release. By these criteria LfN was found to be correctly processed, glycosylated, and able to bind iron reversibly. Both UV-visible and electron spin resonance spectra of the half molecule were very similar to those of native lactoferrin and the full length lactoferrin produced in BHK cells, but there were marked differences in the pH at which iron release occurred. Iron release from LfN occurs in the pH range 6.0-4.0, compared with 4.0-2.5 for native lactoferrin and 6.2-4.0 for transferrin. These results suggest that the more facile release of iron from LfN compared with native lactoferrin results from the absence of stabilizing contacts between the N- and C-terminal halves and that the characteristic difference in pH stability between lactoferrins and transferrins is due primarily to differences in these interactions.

Amino Acid Sequence↗
PubMed1992

Prognostic factors for local recurrence, metastasis, and survival rates in squamous cell carcinoma of the skin, ear, and lip. Implications for treatment modality selection.

We reviewed all studies since 1940 on the prognosis of squamous cell carcinoma (SCC) of the skin and lip. The following variables are correlated with local recurrence and metastatic rates: (1) treatment modality, (2) prior treatment, (3) location, (4) size, (5) depth, (6) histologic differentiation, (7) histologic evidence of perineural involvement, (8) precipitating factors other than ultraviolet light, and (9) host immunosuppression. Local recurrences occur less frequently when SCC is treated by Mohs micrographic surgery. This local recurrence rate differential in favor of Mohs micrographic surgery holds true for primary SCC of the skin and lip (3.1% vs 10.9%), for ear SCC (5.3% vs 18.7%), for locally recurrent (previously treated) SCC (10% vs 23.3%), for SCC with perineural involvement (0% vs 47%), for SCC of size greater than 2 cm (25.2% vs 41.7%), and for SCC that is poorly differentiated (32.6% vs 53.6%).

Carcinoma, Squamous Cell↗
PubMed1989

Long-term recurrence rates in previously untreated (primary) basal cell carcinoma: implications for patient follow-up.

We reviewed all studies (since 1947) reporting recurrence rates for treatment of primary (previously untreated) basal cell carcinomas using surgical excision, radiotherapy, cryotherapy, curettage and electrodesiccation, and Mohs micrographic surgery. Our findings indicate that recurrences following treatment of primary basal cell carcinoma appear later than is generally acknowledged in the literature. We found that less than one-third of all recurrences appear in the first year following treatment; only 50% appear within the first 2 years following treatment; and only 66%, or nearly two-thirds, appear within the first 3 years following treatment. A good rule of thumb is that the 10-year recurrence rate is double, or 2 times, that of the 2-year recurrence rate. Furthermore, 18% of recurrences appear between the fifth and tenth year following treatment. These results held true, irrespective of treatment modality examined. Seventy-two studies reporting short-term recurrence rates (follow-up less than 5 years) had a weighted average recurrence rate of 4.2%, whereas 34 long-term studies (follow-up of 5 years) had a weighted average recurrence rate of 8.7%, or more than 2 times the short-term rate. Five-year recurrence rates by treatment modality are as follows: Mohs micrographic surgery 1.0%, surgical excision 10.1%, curettage and electrodesiccation 7.7%, radiation therapy 8.7%, and cryosurgery 7.5%. We conclude that the reporting of recurrence rate data for basal cell carcinoma should be standardized using 5-year life table analysis, and even more important is our conclusion that lifetime follow-up is necessary after treatment of primary basal cell carcinoma in order both recurrences and new primaries.

Basal Cell Carcinoma↗
PubMed1989

Mohs surgery is the treatment of choice for recurrent (previously treated) basal cell carcinoma.

We reviewed all studies (since 1945) reporting recurrence rates for treatment of recurrent (previously treated) basal cell carcinomas (BCC) using surgical excision, radiotherapy, cryotherapy, curettage and electrodesiccation, and Mohs micrographic surgery. The 5-year recurrence rate for Mohs micrographic surgery is 5.6%. The recurrence rate for non-Mohs modalities of 19.9% is nearly four times higher. Individual recurrence rates for the non-Mohs modalities are 17.4% for surgical excision, 40.0% for curettage and electrodesiccation, and 9.8% for radiation therapy. There are no studies reporting 5-year data for cryotherapy. However, the recurrence rate is 13.0% for cryotherapy when the follow-up period is less than five years. The data support the following conclusions: (1) Mohs surgery is the treatment of choice for recurrent BCC; (2) if the patient is not a surgical candidate and the lesion is small, radiation therapy is an alternative that offers a better chance for cure than the other non-Mohs modalities; and (3) curettage and electrodesiccation should not be used to treat recurrent basal cell carcinoma.

Basal Cell Carcinoma↗
PubMed1987

Social drinking and cognitive functioning in college students: a replication and reversibility study.

The purposes of this study were to replicate a previous study of the relationship between alcohol consumption and cognitive functioning in college students and to investigate the reversibility of negative effects of social drinking on cognitive functioning when randomly assigned subjects abstained from drinking for 2 weeks. The previous study was replicated by administering the same battery of neuropsychological tests to 170 subjects (103 women) during the first testing session. Like the original study, the present study demonstrated several significant predicted inverse relationships between drinking and cognitive performance, but specific relationships between various drinking and cognitive variables were not replicated. As in the original study, some significant nonpredicted relationships also occurred. At the end of the first testing session, subjects were randomly assigned either to abstain from drinking or to maintain their usual drinking patterns for 2 weeks. They were then administered a different neuropsychological battery designed to assess functions similar to the original battery. Consumption the previous 2 weeks was significantly lower in the abstain group than in the maintain group, but there were no significant differences in the predicted direction between groups on the cognitive variables. Several significant predicted inverse correlations between drinking variables and cognitive performance occurred, but some nonpredicted relationships occurred also. Problems and implications for research in social drinking are discussed.

Adult↗
PubMed1986

Eruptive widespread Spitz nevi.

A 12-year-old girl was evaluated for a widespread eruption of Spitz nevi. Multiple Spitz nevi are rare, and this variant is exceedingly rare. The reported cases of eruptive nevi of all types are briefly reviewed. Very little is known regarding cause, natural history, or treatment. Cutaneous stimulation occurring in a genetically predisposed individual is the proposed essential causative factor in this disorder.

Child↗
PubMed1986

Prognosis of clinical stage I melanoma patients with positive elective regional node dissection.

We tested 12 clinical and histologic variables to see which ones best predicted death from melanoma in 66 patients with positive elective regional node dissections (clinical stage I, pathologic stage II [CSI, PSII]). Despite the presence of lymph node metastases, not all patients had poor prognoses. Patients with tumors less than or equal to 3.5 mm and a percentage of positive nodes less than or equal to 20% had a 7-year survival rate of 66%. Within this low-risk group the subset with primary lesions on the trunk or extremities (except hands and feet) had a 7-year survival rate of 76%. This compares with poor 7-year survivals of 29% and 30% observed in other defined high-risk groups. Our results confirm and extend earlier observations concerning the prognoses of CSI, PSII melanoma patients and are relevant to any ongoing and future studies concerning elective regional node dissection (ERND) or adjuvant therapy trials in melanoma.

Actuarial Analysis↗
PubMed1985

Alcohol use and cognitive functioning in men and women college students.

Two studies of the relationship between alcohol consumption and cognitive functioning in men and women college students are presented. Study 1 showed several predicted relationships of decreased cognitive performance on various tests with increased quantity of alcohol per occasion and total lifetime consumption in both women and men. Study 2a was designed to replicate study 1, but the pattern of relationship of cognitive and consumption variables was quite different, e.g., increased cognitive performance was associated with increased quantity per occasion for several tests in males. Study 2b was designed to demonstrate reversibility of the negative effects of consumption on cognition by randomly assigning half of the subjects to abstain for two weeks. Reversibility was not demonstrated. Difficulties in studying these effects in college students are discussed.

Adult↗
PubMed1985

Expression of activation antigens by T cells infiltrating basal cell carcinomas.

The association of T lymphocytes and dendritic cells with the stromal mononuclear cell response to basal cell carcinomas has led to speculation that cellular immunity may, in part, regulate the growth and development of this neoplasm. It has not been established, however, whether these T cells are functionally competent, or simply coincidental bystanders. We examined the immunologic phenotypes of mononuclear cells in 32 lesions of basal cell carcinoma obtained from 26 patients. The majority of infiltrating mononuclear cells were T cells that were equally distributed between the helper/inducer (Leu 3a+) and cytotoxic/suppressor (Leu 2a+) subtypes; a minority of cells were dendritic and expressed Leu 6 antigen. Virtually all T cells and dendritic cells were HLA-DR+, and many (greater than 30%) of the T cells expressed antigens consistent with stages of ongoing activation (T9, T10). TS2/7, a novel monoclonal antibody recently documented to identify activation-specific subcomponents of 210/165/130 kD glycoprotein complex present on the surface of mitogen- or alloantigen-stimulated human T cells, was also used. Greater than 50% of the T cells observed were TS2/7+. These observations provide in situ immunomorphologic evidence of stromal T cell activation in association with basal cell carcinomas, and suggest a role for active and ongoing cellular immune mechanisms as a determinant of local biological behavior of this neoplasm.

Antibodies, Monoclonal↗
PubMed1985

Malignant melanoma prognostic factors 7: elective lymph node dissection.

Every prospective study published to date, whether randomized or nonrandomized, shows that the survival rate for patients with clinical stage I melanoma is the same, irrespective of whether they have an elective lymph node dissection (ELND). All the studies that purport to show a survival benefit from ELND have been based on retrospective data and are therefore subject to selection bias. Nevertheless, the data support the notion that there may be a small, select group of melanoma patients whose lives can be saved by ELND. This subgroup is made up of those patients who have epithelioid in small nests (ESN) melanomas. In the early stages of its evolution, this type of malignant melanoma metastasizes to regional lymph nodes and often does not have coexistent distant metastases. Other types of melanomas, when they metastasize, either bypass the lymph nodes or metastasize to the lymph node and simultaneously send distant metastases elsewhere, nullifying the anticipated benefit from an ELND. We encourage dermatologists, when they have a choice, to be supportive of those surgeons who have a choice, to be supportive of those surgeons who are actively participating in ongoing randomized trials designed to select patients who might benefit from ELND.

Analysis of Variance↗
PubMed1984

Cigarette smoking and malignant melanoma. Prognostic implications.

Heavy cigarette smoking (current smoking with greater than 15-pack-year smoking history), along with 13 other variables, were tested for their ability to predict death in 196 patients with clinical Stage I melanoma. A stepwise proportional hazards general linear model (Cox multivariate analysis) showed that although heavy cigarette smoking as a single variable is an adverse prognostic marker (P = 0.0065), it has only suggestive prognostic significance once thickness factors are taken into account (P = 0.0747). People who stopped smoking had the same survival as nonsmokers. Clinical Stage I patients with melanoma who were heavy smokers presented with thicker lesions than their nonsmoking counterparts (P = 0.037). Although cigarette smoking may play a role in the biologic behavior of melanoma by mediating an effect on thickness, it need not be considered as an independent stratification criterion when analyzing results of melanoma prognosis or treatment.

Adult↗
PubMed1984

"Microscopic satellites" are more highly associated with regional lymph node metastases than is primary melanoma thickness.

A multivariate analysis was performed on 20 clinical and histologic variables from 327 Stage I prospectively studied melanoma patients who underwent elective regional lymph node dissection (ERLD). Primary tumor thickness, microscopic satellites, and the elapsed interval between diagnosis and ERLD, were selected as the combination of variables that were most highly associated with clinically occult regional lymph node metastases (P = 10(-15), model chi-square). Microscopic satellites were defined as tumor nests, greater than 0.05 mm in diameter, in the reticular dermis, panniculus, or vessels beneath the principal invasive tumor mass but separated from it by normal tissue on the section in which the Breslow measurement was taken. The probability of finding nodal metastases for melanomas less than 0.75 mm thick was 0% (0/41 patients); for those 0.76-1.50 mm, 4% (4/108); 1.51-3.0 mm, 14% (14/102); and greater than 3.0 mm, 39.5% (30/76). Primary melanomas greater than 1.50 mm thick with microscopic satellites were more often associated with nodal metastases than those of similar thickness without satellites (30/57 (53%) versus 14/121 (12%), P = 0.01). Some satellites probably represent intraspecimen metastases, while others do not. Any predictive model for occult regional lymph node metastases based on data from ERLD done less than 50 days after diagnosis may underestimate the prevalence of metastases.

Adult↗
PubMed1984

Malignant melanoma prognostic factors 5: clinical staging.

Regional lymph node enlargement, as determined by palpation, is a useful prognostic factor--even if these nodes are histologically free of metastases. This is true not only for malignant melanoma but also for mycosis fungoides and carcinoma of the vulva.

Analysis of Variance↗