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PubMedDate not supplied

Competing demands in the office visit: what influences mammography recommendations?

BACKGROUND: The multiple competing demands of the busy office visit have been shown to interfere with delivery of preventive services. In this study we used physician recommendations for screening mammography to examine the relative importance of physician, patient, and visit characteristics in determining on which patient visits this preventive service will be provided. METHODS: Physicians in the Ambulatory Sentinel Practice Network (ASPN) completed a questionnaire describing their knowledge, attitudes, and beliefs about screening mammography. They also described the content of a series of nonacute care visits with women aged 40 to 75 years with regard to making a recommendation when the patient was due for screening mammography. The data were linked, and univariate and multivariate logistic regression methods were used to examine the relative importance of physician, patient, and visit characteristics on making a recommendation for mammography. RESULTS: Ninety-three physicians reported making a recommendation for screening mammography on 53.1% of nonacute visits. When modeling physician, patient, and visit characteristics separately, 70% of the variability in the model is explained by physician characteristics only, 63% by patient characteristics only, and 73% by visit characteristics only. A combined model using all characteristics explained 85% of the variability. CONCLUSIONS: Although characteristics of physicians and patients can predict frequency of recommendations for mammography, the specific characteristics of the visit are equally important. Efforts to improve delivery of preventive services in primary care that emphasize physician education and performance feedback are unlikely to increase rates of mammography recommendation. Effective strategies must consider the multiple competing demands faced by patients and physicians during each office visit and seek ways for assisting them in setting rational priorities for services.

Attitude of Health Personnel↗
PubMedDate not supplied

Immunohistochemical and ultrastructural classification of peripheral neuropathies with onion-bulbs.

By immunochemically and ultrastructurally identifying cellular components of onion-bulbs (Obs), this study attempts to delineate and classify types of hypertrophic neuropathies which are otherwise obscured by proliferation of the morphologically similar cells forming Obs. Fourteen cases with different forms of chronic localized or generalized hypertrophic neuropathy with Obs were retrospectively studied to include: one Dejerine-Sottas (D-S); two Charcot-Marie-Tooth (CMT); three chronic inflammatory demyelinating polyneuropathy (CIDP); one inflammatory localized hypertrophic mononeuritis (LHM); two perineuriomas (PNM); one traumatic amputation neuroma (TAN); one chronic diabetic neuropathy (CDN); two neurofibromas (NF); and one chronic arsenic polyneuropathy (AsPN). By immunostaining with 7 selected antibodies, we can distinguish at least 4 nosologically distinct types of neuropathy by identifying cellular components of given Obs: 1) primarily Schwann cells with no perineurial cells or macrophages in CMT or D-S, 2) predominantly Schwann cells, activated macrophages and a few fibroblasts in CIDP and LHM, 3) primarily perineurial and a few central Schwann cells with no macrophages in PNM and TAN, and 4) exclusively perineurial cells in the hamartomatous PNM associated with NF.

Adolescent↗
PubMed1991

Purification and primary structure of C-1027-AG, a selective antagonist of antitumor antibiotic C-1027, from Streptomyces globisporus.

C-1027-AG, a selective antagonist of antitumor antibiotic C-1027, was isolated by column chromatography on DEAE-cellulose, butyl-Toyopearl and Sephadex G-50 from a culture filtrate of Streptomyces globisporus. The amino acid sequence of purified C-1027-AG was determined with a protein sequencer on the basis of fragment peptides obtained by enzymatic hydrolysis with lysylendopeptidase, V8 protease, endopeptidase AspN and chymotrypsin, after performic acid oxidation. C-1027-AG is shown to consist of a single polypeptide chain cross-linked by two disulfide bonds, and to contain a total of 110 amino acid residues with alanine and glycine as its amino- and carboxyl-termini, respectively; its molecular weight was calculated to be 10,500 daltons. The primary structure of C-1027-AG is indicated to be identical to the protein moiety of C-1027, and is highly homologous to the sequences of antitumor proteins obtained from other Streptomyces species.

Amino Acid Sequence↗
PubMed1991

Amino acid sequence and post-translational modification of stem cell factor isolated from buffalo rat liver cell-conditioned medium.

Stem cell factor (SCF) isolated from culture medium conditioned by Buffalo rat liver cells was subjected to detailed structural analysis. Attempts at direct N-terminal sequencing of the factor indicated that its N terminus is blocked as pyroglutamic acid (Zsebo, K. M., Wypych, J., McNiece, I. K., Lu, H. S., Smith, K. A., Karkare, S. B., Sachdev, R. K., Yuschenkoff, V. N., Birkett, N. C., Williams, L. R., Satyagal, V. N., Bosselman, R. A., Mendiaz, E. A., and Langley, K. E. (1990) Cell 63, 195-201). The removal of the blocking pyroglutamate by pyroglutamate aminopeptidase allowed sequencing of the polypeptide chain to position 47. Stem cell factor was also digested with CNBr, trypsin, Staphylococcus aureus protease (strain V8), and AspN peptidase to generate different sets of peptides that were then separated by reverse-phase high-performance liquid chromatography and sequenced. Sequence of an internal peptide fragment obtained by cleavage of stem cell factor at a single tryptophanyl peptide bond was also obtained. From these analyses, the complete amino acid sequence could be constructed. The factor as isolated is a single polypeptide of 164 or 165 amino acids. The sequence is confirmatory to a sequence deduced from a cDNA sequence and provides important evidence for C-terminal processing of the polypeptide encoded by cDNA. There are four potential N-linked glycosylation sites. Asn65, Asn72, Asn109, and Asn120. Sequence determination of isolated peptides suggested that Asn120 is glycosylated, Asn65 and Asn109 glycosylated in some molecules but not in others, and Asn72 not glycosylated. Amino acids at three positions, i.e. 142, 143, and 155, could not be detected during sequence analysis. Since the gene sequence codes for Ser, Thr, and Thr at these positions (Martin, F. H., Suggs, S. V., Langley, K. E., Lu, H. S., Ting, J., Okino, K. H., Morris, C. F., McNiece, I. K., Jacobsen, F. W., Mendiaz, E. A., Birkett, N. C., Smith, K. C., Johnson, M. J., Parker, V. P., Flores, J. C., Patel, A. C., Fisher, E. F., Erjavec, H. O., Herrera, C. J., Wypych, J., Sachdev, R. K., Pope, J. A., Leslie, I., Wen, D., Lin, C. W., Cupples, R. L., and Zsebo, K. M. (1990) Cell 63, 203-211), they could be sites of O-linked carbohydrate attachment. The four cysteines form two intramolecular disulfide bonds, Cys4-Cys89 and Cys43-Cys138.

Amino Acid Sequence↗
PubMed1991

Amino acid sequence of rabbit apolipoprotein E.

The complete amino acid sequence of rabbit apolipoprotein E (apoE) was determined by generating three sets of peptides using cyanogen bromide, endoproteinase AspN, and Staphylococcus aureus V8 protease to cleave the protein. Through twenty cycles of sequence analysis on the whole protein, glutamic acid was identified as the N-terminal residue of rabbit apoE; the C-terminus of the protein was identified as glutamine. Based on the sequence of 294 amino acid residues determined by protein structure analysis, the molecular weight of rabbit apoE was determined to be 33,684. The protein sequence differed from the cDNA inferred sequence in 19 positions, only one of which could be attributed to microheterogeneity. The corrected amino acid sequence of rabbit apoE shares 80% homology with the human apoE sequence, 4% greater homology than that inferred from the cDNA sequence. The great similarity in the amino acid sequences of human and rabbit apoE suggests that their physical and physiological properties may also be similar. This homology and the relative ease with which apoE is isolated from rabbit plasma make it possible to conduct some in vitro experiments with the rabbit apoprotein that would have direct relevance to human apoE, but would be difficult or impossible with the human counterpart because of the quantity of protein required.

Amino Acid Sequence↗
PubMedDate not supplied

Confirming the primary structures of insulin-like growth factors 1 and 2 isolated from porcine plasma using mass analysis.

The amino acid sequences of insulin-like growth factors 1 and 2 from porcine plasma have been determined by mass analysis of peptides obtained from tryptic and AspN digests for the former protein and from tryptic and peptic digests for the latter. Complete homology to the human Type 1 protein was indicated by the overlapping peptide map obtained by mass analysis. For the Type 2 protein, a mutation of a Ser in the human protein to an Asn in the porcine was confirmed by the combination of mass analysis and automated protein microsequencing. The studies were performed on 3 micrograms (0.4 nmol) of each protein, indicating the sensitive potential of this method in primary structure-homology studies.

Amino Acid Sequence↗
PubMedDate not supplied

Age/sex registries in primary care research.

Age/sex registries have been examined as a method of estimating the number of individuals served by a primary care practice. These data can be used in estimating disease frequency from primary care encounter data. The experience with age/sex registries in the Ambulatory Sentinel Practice Network (ASPN) has identified three major sources of error when registry data are used to estimate disease rates: (1) studies using medical encounter data exclude those individuals who do not seek medical care, (2) visitation is not random and is a function of variables in addition to disease incidence, and (3) encounter data from primary care practices are incomplete due to reporting problems and patient-initiated visits to other health care providers. Despite these limitations, age/sex registries can provide a practical tool for estimating disease rates in appropriate settings, assessing the generalizability of results, and assessing the feasibility of studies in practice based research. Further research about age/sex registries is needed to improve disease rate estimation as well as to better define methods. An age/sex registry enumerates a population by age and sex categories. Such a registry of the patients cared for by a medical practice represents a useful tool for practice based research. This paper briefly reviews the background of age/sex registries in North America, describes the experience of the Ambulatory Sentinel Practice Network with age/sex registries, identifies problems in using age/sex registries to provide denominator data for disease frequency estimation, and explores other uses for age/sex registry data.

Adolescent↗
PubMedDate not supplied

Verification of data reported by practices for a study of spontaneous abortion.

Little is known about the accuracy of data reported in practice based primary care research. The Ambulatory Sentinel Practice Network (ASPN) undertook a 100% audit of 226 patients included in a study of spontaneous abortion (SAB). The audit was conducted to assess the feasibility of conducting audits in primary care research networks dispersed over large geographic areas, verify that patients met inclusion criteria, and assess the frequency of reporting errors using the medical record as a standard. Of the originally reported SABs, 24% could not be verified. The overall error rate was 4.5%, a total of 106 errors out of a possible 2,361. Seventy percent of these errors came from five of the 34 participating practices. Sixty-six percent of the records were error-free. Seventy-seven percent of the errors were associated with problems with methods and clustered into three categories: gravidity, gestational age, and dilation and curettage (D&C). According to this audit, the data reported by the practices for research purposes were very similar to the data found in the medical record.

Abortion, Spontaneous↗
PubMedDate not supplied

The International Primary Care Network: purpose, methods, and policies.

The International Primary Care Network (IPCN), a consortium of practice based primary care research networks, including the Ambulatory Sentinel Practice Network (ASPN), is described. The purpose, methods, and policies are presented as an example of international networking to address problems of global concern in primary care. IPCN's experience with organizing a framework for collaboration and conducting a study of otitis media in nine countries suggests that efforts of this type are possible and may lead to new insights available only through international investigation.

Ambulatory Care Information Systems↗
PubMed1994

[Structure of peptide fragments of the complex (Lys(Abz)26) neurotoxin II from Naja naja oxiana cross-linked with the nicotinic acetylcholine receptor from Torpedo californica].

After irradiating the acetylcholine receptor complex with the title neurotoxin derivative, the labeled delta-subunit was separated by preparative SDS-PAGE, reduced-carboxymethylated and cleaved with LysC endoproteinase. One of the radioactive peptides isolated by HPLC was further purified by electrophoresis in a tricin gel. Edman degradation of the radioactive fractions yielded the sequence of the delta-subunit fragment starting from Phe148. The AspN-cleavage of the radioactive peptide from the LysC digest gave on HPLC a radioactive peak which eluted similarly to peptide 33-44 generated by LysC/AspN-cleavage of 125I-neurotoxin II. In model experiments, irradiation of the photoactivable derivative was found to produce a heterogeneous mixture of reaction products. Unusually low initial and repetitive yields were observed for neurotoxin II and its fragments containing the photolabeled and radiolabeled residues. These results might explain why the neurotoxin sequence was not detected on Edman degradation of the cross-linked products available at a low picomole level.

Amino Acid Sequence↗
PubMed1996

Toward optimal laboratory use. Problems in laboratory testing in primary care.

OBJECTIVE: To examine the frequency and characteristics of problems in laboratory testing in primary care physicians's offices and their impact on health care. DESIGN: Prospective descriptive study in which participating office-based primary care clinicians reported each occurrence of any laboratory incident during a 6-month study. Each identified problem was reported on a structured data collection instrument with an open-ended description of the problem. SETTING: Primary care physicians' offices in North America. PARTICIPANTS: One hundred twenty-four primary care clinicians in 49 practices of the Ambulatory Sentinel Practice Network (ASPN). MAIN RESULTS: A total of 180 problems were reported, yielding a crude rate of 1.1 problems per 1000 patient visits. Problems involving test ordering and specimen handling were the most common (56%), while those attributable to the test analysis itself accounted for 13% of the total. In the judgment of the practice staff, 27% of the reported problems had an impact on patient care. Of the 24 cases for which the specific impact was known and reported, half of the impacts were minor and about half were significant, as judged by whether or not the diagnosis and/or treatment of the patient was measurably affected. CONCLUSIONS: Clinically apparent problems with laboratory testing in primary care were found at a rate of 1.1 problems per 1000 patient visits. Of the laboratory problems that occurred in this study, 27% were judged by the physician to have an effect on patient care.

Clinical Laboratory Techniques↗
PubMed1976

Chronic neurologic disturbance in childhood leukemia.

Twenty-three leukemic children were studied prospectively to detect chronic effects of therapy. All patients received CNS prophylaxis, including 2400 R cranial irradiation, and intermittent maintenance therapy with intravenous methotrexate, cyclophosphamide and cytosine arabinoside. Neurologic symptoms were observed in 12 patients, all of whom had intermittent limping and mild incoordination, between the 10th and 18th month of maintenance therapy. Five of the 12 sustained seizures and four of these had subsequent abnormalities in motor, perceptual, behavioral or language development. Three school-aged children have learning disability and perceptual-motor defects. Studies of CSF folate and MTX content are presented but not helpful in delineating the etiology of these neurologic symptoms.

Adolescent↗
PubMed1979

Methotrexate and asparaginase combination chemotherapy in refractory acute lymphoblastic leukemia of childhood.

Two groups of children with refractory acute lymphoblastic leukemia were treated with a regimen of methotrexate (MTX) and asparaginase (Asn'ase) based on studies of the effect of MTX in vitro on human lymphoblasts exposed to Asn'ase. Induction therapy in 12 children produced 4 complete remissions, 3 partial remissions, and 5 failures. Responsiveness to Asn'ase seemed necessary for successful induction with the drug combinations. Maintenance therapy in 18 children produced a median hematologic remission of 31 weeks (range 3-85 weeks). During remission, 2 children developed central nervous system leukemia and 2 died of infection. The mean maximally tolerated dose of MTX was 361 mg/m2. The results of this trial suggest therapeutic synergy in maintenance therapy and the capability of Asn'ase to attenuate MTX toxicity.

Adolescent↗
PubMed1976

Prospective study of sickle cell anemia in infancy.

Twelve infants with sickle cell anemia identified in the course of a cord blood screening program have been followed prospectively for up to three years of age. The development of hemolytic anemia paralleled the postnatal decline in fetal hemoglobin and was evident in all infants by 12 weeks of age. Vasoocclusive episodes occurred in more than half the infants and seven aplastic crises were documented in four patients. Febrile illnesses were common and one of the twelve infants developed pneumococcal sepsis. This study also demonstrated that functional asplenia is an acquired defect in sickle cell disease. The onset of functional asplenia was documented with splenic scans in six of the nine infants followed for more than one year after birth. There have been no deaths in this series.

Anemia, Aplastic↗
PubMed1999

Proximal electromagnetic shear forces.

We perform a simple model calculation to estimate the electromagnetically induced shear force caused by a current dissipation when a charged tip is moved parallel to a conducting material. For parameters typical in shear force imaging, the force is many orders of magnitude below reported values. Thus, proximal electromagnetic tip-sample forces can be neglected in discussions of shear force imaging.

Journal Article↗
PubMed2002

A combinatorial toolbox for protein sequence design and landscape analysis in the grand canonical model.

In modern biology, one of the most important research problems is to understand how protein sequences fold into their native 3D structures. To investigate this problem at a high level, one wishes to analyze the protein landscapes, i.e., the structures of the space of all protein sequences and their native 3D structures. Perhaps the most basic computational problem at this level is to take a target 3D structure as input and design a fittest protein sequence with respect to one or more fitness functions of the target 3D structure. We develop a toolbox of combinatorial techniques for protein landscape analysis in the Grand Canonical model of Sun, Brem, Chan, and Dill. The toolbox is based on linear programming, network flow, and a linear-size representation of all minimum cuts of a network. It not only substantially expands the network flow technique for protein sequence design in Kleinberg's seminal work but also is applicable to a considerably broader collection of computational problems than those considered by Kleinberg. We have used this toolbox to obtain a number of efficient algorithms and hardness results. We have further used the algorithms to analyze 3D structures drawn from the Protein Data Bank and have discovered some novel relationships between such native 3D structures and the Grand Canonical model.

Algorithms↗
PubMed1997

Influence of fat intake and caloric restriction on bone in aging male rats.

Caloric and fat intake may have important skeletal consequences. To evaluate this possibility, skeletal effects of adult-onset caloric restriction (CR) at differing fat intakes were assessed in male Lobund-Wistar rats. At age 17 months, two groups of animals received an anti-obesity diet, restricted approximately 35% from individual ad libitum baseline calorie consumption, and two groups received a diet approximately 50% restricted. Dietary fat concentrations were 5, 15, 15, and 25% by weight, respectively. At ages 20, 24, 28, 30, and 32 months, ex vivo femoral bone densitometry and serum biochemical analyses were performed. Body weight (BW) decreased with time on CR in each group (p < .005), declining faster at the more severe restriction (p = .001). Femoral bone mineral contents (BMC) were also reduced. After adjusting for bone area and BW differences among groups, the only significant difference was a reduction in distal femur BMC in the 25% fat group subjected to more severe CR (p = .02). No differences were observed in serum parathyroid hormone, calcium, phosphorus, or creatinine. Femoral bone loss occurred with CR. This was entirely accounted for by reduction in BW. Higher dietary fat content did not affect BW in CR animals, but did result in lower distal femur BMC.

Aging↗