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Biomedical subjects

D Knapp

Publications and source records attributed to D Knapp.

At least 19 recordsLinked to original sources
PubMed1998

Comparison of the characteristics and features of pressure garments used in the management of burn scars.

Two companies provide custom-made pressure garments to clients with burn scars at Westmead Hospital. This prospective study was completed in order to make objective decisions about which garments were most appropriate and cost effective to provide to clients. Issues such as cost, durability, fit and client preferences were investigated. Data were collected from 43 clients; at the time of initial fitting, at a follow-up appointment 4-6 weeks later, and at the time one of the garments required replacement. One Second Skin and one Jobst garment were provided to each client and the garments were compared using therapists' evaluation and clients' perspectives on a number of variables. Second Skin garments had significantly more favourable results on the variables of time for delivery, fit at follow-up, garment design, quality of fabric and seams, overall satisfaction and garment preference for ongoing wear. On all other variables there was no significant difference between the garments. Second Skin provided the most optimal and appropriate option for pressure garments in the management of burn scars for our clients.

Adolescent↗
PubMed1997

Loading of an Mcm protein onto DNA replication origins is regulated by Cdc6p and CDKs.

In eukaryotic cells, firing of DNA replication origins normally does not recur until after M phase. This characteristic is thought to be due to the properties of "initiation" proteins like Orc, Cdc6, and Mcms. Using formaldehyde cross-linking, we show that Cdc6p and Mcm7p associate specifically with replication origins during G1 but not during G2 in S. cerevisiae. Mcm7p's association with origins depends on Cdc6p. Ectopic expression of Cdc6p enables it to associate with origins during G2, but this fails to recruit Mcm7p. Our data suggest that the loading of Mcm proteins onto origins is regulated by two mechanisms: first, by Cdc6p occupancy, and second, by S- and M-CDKs, whose activity during S, G2, and M phases prevents Mcm loading.

Binding Sites↗
PubMed1997

Crystal structure of the DNA-binding domain of Mbp1, a transcription factor important in cell-cycle control of DNA synthesis.

BACKGROUND: During the cell cycle, cells progress through four distinct phases, G1, S, G2 and M; transcriptional controls play an important role at the transition between these phases. MCB-binding factor (MBF), a transcription factor from budding yeast, binds to the so-called MCB (MluI cell-cycle box) elements found in the promoters of many DNA synthesis genes, and activates the transcription of those at the G1-->S phase transition. MBF is comprised of two proteins, Mbp1 and Swi6. RESULTS: The three-dimensional structure of the N-terminal DNA-binding domain of Mbp1 has been determined by multiwavelength anomalous diffraction from crystals of the selenomethionyl variant of the protein. The structure is composed of a six-stranded beta sheet interspersed with two pairs of alpha helices. The most conserved core region among Mbp1-related transcription factors folds into a central helix-turn-helix motif with a short N-terminal beta strand and a C-terminal beta hairpin. CONCLUSIONS: Despite little sequence similarity, the structure within the core region of the Mbp1 N-terminal domain exhibits a similar fold to that of the DNA-binding domains of other proteins, such as hepatocyte nuclear factor-3gamma and histone H5 from eukaryotes, and the prokaryotic catabolite gene activator. However, the structure outside the core region defines Mbp1 as a larger entity with substructures that stabilize and display the helix-turn-helix motif.

Amino Acid Sequence↗
PubMed1996

Immunohistochemical staining for markers of future neoplastic progression in the larynx.

We performed a retrospective, longitudinal study to determine whether abnormalities in immunohistochemical staining for the epidermal growth factor receptor (EGFR), p53, or cyclin D1 occur before the development of laryngeal carcinoma. Staining was performed on 63 paraffin-embedded biopsies from 18 patients who subsequently developed carcinoma in situ (CIS) or invasive carcinoma of the larynx. These were compared to 71 biopsies from 20 patients who did not develop CIS/cancer (minimum follow-up period, 4 years). Also studied were the 34 biopsies containing CIS and/or carcinoma from those patients who progressed and 22 biopsies obtained concurrently. The two patient groups did not differ significantly in terms of tobacco and alcohol use. Distinct patterns of staining correlated with malignant progression. These included EGFR staining of two thirds or more of the epithelium thickness, a linear basal p53 staining pattern, and strong (3+) staining for cyclin D1 (P < 0.01 for each). These staining patterns also correlated with increasing atypia. In our study population, linear basal staining for p53 and strong staining for cyclin D1 had higher specificity for progression than did EGFR overexpression, which was also seen in association with inflammation and chronic irritation. Marked site-to-site variation was seen in the immunohistochemical staining and in the degree of atypia, suggesting that multiple biopsies are necessary to properly assess risk. These immunohistochemical staining patterns may be clinically useful to predict patients at risk for neoplastic progression.

Adult↗
PubMed1996

The transcription factor Swi5 regulates expression of the cyclin kinase inhibitor p40SIC1.

DNA replication in budding yeast cells depends on the activation of the Cdc28 kinase (Cdk1 of Saccharomyces cerevisiae) associated with B-type cyclins Clb1 to Clb6. Activation of the kinase depends on proteolysis of the Cdk inhibitor p40SIC1 in late G1, which is mediated by the ubiquitin-conjugating enzyme Cdc34 and two other proteins, Cdc4 and Cdc53. Inactivation of any one of these three proteins prevents p40SIC1 degradation and causes cells to arrest in G1 with active Cln kinases but no Clb-associated Cdc28 kinase activity. Deletion of SIC1 allows these mutants to replicate. p40SIC1 disappears at the G1/S transition and reappears only after nuclear division. Cell cycle-regulated proteolysis seems largely responsible for this pattern, but transcriptional control could also contribute; SIC1 RNA accumulates to high levels as cells exit M phase. To identify additional factors necessary for the inhibition of the Cdk1/Cdc28 kinase in G1, we isolated mutants that can replicate DNA in the absence of Cdc4 function. Mutations in three loci (SIC1, SWI5, and RIC3) were identified. We have shown that high SIC1 transcript levels at late M phase depend on Swi5. Swi5 accumulates in the cytoplasm during S, G2, and M phases of the cell cycle but enters the nuclei at late anaphase. Our data suggest that cell cycle-regulated nuclear accumulation of Swi5 is responsible for the burst of SIC1 transcription at the end of anaphase. This transcriptional control may be important for inactivation of the Clb/Cdk1 kinase in G2/M transition and during the subsequent G1 period.

Base Sequence↗
PubMed1995

Promyelocytic blast crisis of chronic myelogenous leukemia. A rare subtype associated with disseminated intravascular coagulation.

Two patients with chronic myelogenous leukemia (CML) developed blast crisis that morphologically appeared to be the microgranular variant of acute promyelocytic leukemia. This represented 8% of CML patients developing blast crisis from 1984 to 1993. Cytogenetic studies revealed translocation 15;17 in addition to translocation 9;22 that had been documented at initial diagnosis. Both patients had evidence of disseminated intravascular coagulation at the onset or during treatment of blast crisis, which was not documented in any other patients with CML blast crisis. One patient died of sepsis during intensive chemotherapy. The second returned to a chronic phase of the disease after therapy. Although rare, a promyelocytic blast crisis of CML can occur which, as in de novo acute promyelocytic leukemia, has a propensity to produce disseminated intravascular coagulation.

Adult↗
PubMed1995

Cervical lymph node status and survival in laryngeal carcinoma: prognostic factors.

Elective cervical lymphadenectomy often is performed for laryngeal carcinoma to eliminate metastatic disease that escapes clinical and radiographic detection. We investigated characteristics of the primary tumor that might predict cervical lymph node status. We obtained archival tissue from 88 laryngectomies--65 with concurrent cervical lymphadenectomies. Of the 40 clinically negative necks that were dissected, 17% showed lymph node metastasis by pathologic examination. The primary tumors were examined immunohistochemically for expression of epidermal growth factor receptor (EGFR), p53, cathepsin D, proliferating cell nuclear antigen (PCNA), and Ki-67-specific antigen, and by flow cytometry for DNA ploidy-cell cycle analysis. Seventy-seven percent of the cases showed aberrant p53 staining, 99% expressed EGFR, 40% produced cathepsin D, 29% were aneuploid, and 54% had a moderate or high synthesis phase fraction (SPF). High grade, aneuploidy, and tumor vascular invasion independently predicted cervical node metastasis (p < .04 each). Supraglottic locale (p < .16) and a raggedly infiltrating invading margin (p < .13) were weakly associated with node positivity. Advanced clinical T status, the expression of EGFR, p53, and cathepsin D, the PCNA and Ki-67 indices, and SPF did not correlate with node metastasis. The presence of cervical node metastasis predicted poor disease-free (p < .005) and overall survival (p < .04). Advanced clinical T status correlated with brief overall survival (p < .02). Tumor site, histopathologic parameters, ploidy, SPF, PCNA and Ki-67 indices, and the expression of p53, EGFR, and cathepsin D did not affect survival. The presence of vascular invasion, high grade, and aneuploidy may help identify which patients would benefit from elective cervical lymphadenectomy. The correlation of cervical lymph node status and clinical T category with survival confirms the results of previous studies.

Adult↗
PubMed1995

A microwave method that enhances detection of aberrant p53 expression in formalin-fixed, paraffin-embedded tissues.

OBJECTIVE: Detection of aberrantly accumulated p53 protein by immunohistochemistry may have prognostic significance in many human neoplasms. We wished to identify a technique applicable to formalin-fixed, paraffin-embedded sections that would reliably yield results equivalent to frozen-section immunohistochemistry. DESIGN: We compared the frequency of p53 immunostaining obtained by applying monoclonal antibodies PAb1801, DO7, or DO1, a 1:1 PAb1801-DO7 cocktail, and a 1:1 PAb1801-DO1 cocktail to fresh-frozen and formalin-fixed, paraffin-embedded tissues from 36 lung and upper aerodigestive-tract carcinomas. With the formalin-fixed tissues, we compared pepsin predigestion with microwave irradiation in citrate buffer as means of enhancing the sensitivity of p53 detection. SETTING AND PATIENTS: All tissues were obtained from surgical resections of tumors, from patients who underwent surgery at the Minneapolis Department of Veterans Affairs Medical Center between 1990 and 1992. MAIN OUTCOME MEASURES: The sensitivity of different paraffin section techniques for immunohistochemical detection of accumulated p53 protein was determined in reference to the optimal frozen section method (defined as the method that yielded the greatest number of p53-positive cases in frozen tissue). RESULTS: Microwave antigen retrieval markedly enhanced staining with PAb1801 and DO7 in paraffin sections, as compared with pepsin predigestion and no pretreatment. This technique was 100% sensitive relative to the optimal frozen tissue method. In contrast, staining with DO1 alone was not enhanced by microwaving. CONCLUSIONS: Microwave pretreatment in conjunction with the use of either PAb1801 or DO7 is highly efficacious in the immunohistochemical detection of aberrant p53 expression in formalin-fixed, paraffin-embedded tissues.

Antibodies, Monoclonal↗
PubMed1992

Evaluating drug prescribing in a large, ambulatory population: application of an embedded expert system.

DUR is a process of problem detection and intervention designed to improve the quality and economy of drug prescribing. Retrospective DUR attempts to detect and address patterns of prescribing that might be indicative of inappropriate therapy. When the process is extended to a largely ambulatory population such as Medicaid beneficiaries, a number of complications are introduced due to the large numbers of patients and sparsity of data. In order to examine the impact of implementing a Medicaid DUR program, we developed a system that would apply screening criteria to prescription claims. It has been used to screen prescribing of groups of two antihypertensive drugs in the 1990 Maryland Medicaid population for 177,409 Medicaid eligible individuals. Potentially significant problems were detected with respect to dosing, duplication of therapeutic agents and drug interactions. The system represents, we believe, a significant improvement in the ability to detect and report prescribing decisions by increasing the specificity of the detection system. By the application of this system to a set of real-world data, we have demonstrated that it is feasible to implement such a system and derive results that are potentially useful in reducing the incidence of inappropriate physician decision-making.

Ambulatory Care Information Systems↗
PubMed1988

Intraspinal epidermoid cyst in a dog.

A 2-year-old female Rottweiler was examined because of progressive gait deficits consistent with transverse myelopathy between the T2 and L3 spinal cord segments. Myelography confirmed an intramedullary spinal cord lesion between T13 and L1, so the dog was euthanatized. At necropsy, an intramedullary epidermoid cyst was confirmed in the T13 and L1 spinal cord segments. The epidermoid cyst probably resulted from a congenital cause.

Animals↗
PubMed1987

National adverse drug reaction surveillance: 1985.

The Food and Drug Administration received about 37,000 adverse drug reaction reports in 1985. Seventy-one percent of the reports involved toxic reactions to usual doses of drugs and were sent by medical care professionals directly to the Food and Drug Administration or to pharmaceutical manufacturers. In terms of severity, 2% of reports involved death while 21% involved hospitalization. The highest proportions of hospitalization or death were found for reports describing cardiovascular, hematologic, or respiratory effects. Nearly half of the reported deaths were in patients more than 59 years of age. The majority of reports described an adverse drug reaction occurring within two weeks of initial exposure to the suspected drug. Adverse drug reaction reporting by physicians is crucial to ensuring that pharmaceutical products are used appropriately.

Adult↗
PubMed1987

Effect of age and training on aerobic capacity and body composition of master athletes.

Maximum oxygen uptake (VO2max) and body composition have been shown to deteriorate with age. How much of the decline is attributable to aging and how much is affected by reduced physical activity is not known. The purpose of this investigation was to determine the aerobic capacity and body composition of 24 master track athletes and to evaluate the relationship to age and maintenance of training over a 10-yr period. The subjects (50-82 yr of age) were retested after a 10.1-yr follow-up (T2). All continued their aerobic training, but only 11 were still highly competitive (COMP) and continued to train at the same intensity. The other 13 athletes studied became noncompetitive (post-COMP) and reduced their training intensity. The results showed the COMP group to maintain its VO2max and maximum O2 pulse while the post-COMP group showed a significant decline (54.2-53.3 vs. 52.5-45.9 ml X kg-1 X min-1; 20.7-20.8 vs. 22.4-20.0 ml/beat from test one (T1) to T2 for the COMP vs. post-COMP groups, respectively). Maximum heart rate declined 7 beats/min for both groups. Body composition showed no difference between groups from T1 to T2. For both groups body weight declined slightly (70.0-68.9 kg), percent fat increased significantly (13.1-15.1%), and fat-free weight decreased significantly (61.0-59.0 kg). Thus, when training was maintained, aerobic capacity remained unchanged over the follow-up period. Body composition changed for both groups and may have been related to aging and/or the type of training performed.

Aged↗
PubMed1978

Trichophyton simii infection in the United States not traceable to India.

To our knowledge, this communication reports the first case of Trichophyton simii infection in the United States not traceable to India, The patient was a 40-year-old Nigerian male student who had not been out of the United States for more than three years. He had never been in India or had contact with animals or poultry. A brief review of the literature is included.

Adult↗