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Biomedical subjects

D Larson

Publications and source records attributed to D Larson.

At least 19 recordsLinked to original sources
PubMed1992

Evaluation of a Treponema pallidum western immunoblot assay as a confirmatory test for syphilis.

Tests for the detection of antibodies to Treponema pallidum are recommended for the confirmation of reactive nontreponemal test results and the accurate diagnosis of syphilis. The present-day use of Western blot (immunoblot) technology for the diagnosis of retroviruses prompted the development and evaluation of a Western blot assay with whole-cell T. pallidum as the antigen. The assay detected antibodies in syphilitic serum or plasma from dilutions of specimens incubated overnight with test strips. A test was considered positive when at least three of four major antigens having molecular masses of 15.5, 17, 44.5, and 47 kDa were detected. The Western blot assay had 93.8% sensitivity and 100% specificity for clinically defined samples. The Western blot assay was compared with double-staining fluorescent treponemal antibody absorption [FTA-ABS (DS)], which had a sensitivity and a specificity of 91.7 and 92.0%, respectively. Dilution series studies of syphilis-positive specimens indicated that the Western blot assay has an endpoint of reactivity at least 3 to 4 serial dilutions greater than that for FTA-ABS (DS). Overall, the greater than 95% agreement between the Western blot assay and FTA-ABS (DS) for clinically defined specimens indicates that the sensitivity of the Western blot assay is equal to or greater than that of FTA-ABS (DS). The Western blot assay demonstrated no false-positive or equivocal reactivities for nonsyphilitic specimens, including normal specimens (both plasma and serum), biological false-positives, and specimens with elevated gamma globulin or antinuclear antibody. We conclude that the high sensitivity and specificity of the T. pallidum Western blot assay, together with its simplicity and objectivity, make it a good confirmatory test for syphilis.

Animals↗
PubMed1992

Psychosocial and psychopathologic influences on management and control of insulin-dependent diabetes.

The objective of this research was to explore the relationship of psychosocial variables to management and control of insulin-dependent diabetes, as measured by a scale of reported behavioral adherence and by glycosylated hemoglobin, respectively. The method includes a relatively large sample (127 subjects) drawn from a clinic, a broad range of psychosocial variables (depression, anxiety, family process, health locus of control), and documented reliability and validity of psychosocial measurement (alpha coefficients ranging from .63 to .95). The results show that both anxiety and depression have weak positive correlations with blood sugar. Family process variables also are weakly correlated with blood sugar. The measure of behavioral adherence is moderately correlated with blood sugar. The life stage of the diabetic appears to affect these relationships markedly. The conclusion is that there is no broad strong association of psychosocial variables with blood sugar but that there may be subgroups of diabetics, especially adolescents with recent onset, for whom the relationships may be more powerful.

Adolescent↗
PubMed1991

Regional blood-brain barrier transport of cationized bovine serum albumin in awake rats.

Regional blood-brain barrier permeability-surface area products (PAs) of cationized bovine serum albumin (cBSA) with isoelectric point (pI) approximately 8 or greater than or equal to 11 and of native bovine serum albumin (nBSA;pI approximately 4) were determined in awake male Sprague-Dawley rats after bolus intravenous injection. The albumins were labeled with 125I. Brain uptakes were assessed by autoradiography and by direct assay of radioactivity in brain regions. nBSA uptake into brain was statistically insignificant over 3 h, whereas cBSA uptake was significantly even at 6 min. Mean PA values of cBSA with pI approximately 11 (1.69-2.65 x 10(-5) ml.s-1.g-1) in most brain regions were twofold higher than PAs of cBSA with pI approximately 8 (0.98-1.37 x 10(-5) ml.s-1.g-1), whereas mean PA for nBSA did not differ significantly from zero. Autoradiographs of brain slices and net distributions in brain compartments at 6 and 30 min after injection suggested that cBSA entered the brain parenchyma via blood vessels and cerebrospinal fluid but that the former was the main route. The results quantitate for the first time regional brain PA values for cationized proteins and suggest specific mechanisms at cerebral blood vessels that distinguish transport of cationized from noncationized macromolecules.

Animals↗
PubMed1991

Christian Psychiatry: the impact of evangelical belief on clinical practice.

OBJECTIVE: The authors surveyed psychiatrists in the Christian Psychiatry movement to assess the role of religious belief in their practices. METHOD: The psychiatrists were members of the Christian Medical and Dental Society; questionnaires were sent to 260, and usable responses were received from 193. The subjects were asked about demographic and practice variables, "born again" religious experiences, group cohesion, and beliefs about using the Bible and prayer in treatment. RESULTS: The respondents were somewhat more religious than Americans overall, who are themselves more religious than most psychiatrists. Nearly all reported having been "born again," after which they generally experienced a decrease in emotional distress. There was a significant difference in the respondents' affiliative feelings toward psychiatrists in the Christian Psychiatry movement and other psychiatrists. For acute schizophrenic or manic episodes, the respondents considered psychotropic medication the most effective treatment, but they rated the Bible and prayer more highly for suicidal intent, grief reaction, sociopathy, and alcoholism. Whether or not a patient was "committed to Christian beliefs" made a significant difference in whether the respondents would recommend prayer to the patient as treatment. About one-half said they would discourage strongly religious patients from an abortion, homosexual acts, or premarital sex, and about one-third said they would discourage other patients from these activities. CONCLUSIONS: Many studies have suggested a need for more sensitivity to religious issues by psychiatrists, and this study provides systematic findings on one approach. It remains important to evaluate ways in which a religious perspective can be related to clinical practice and what benefits and problems may derive from such a relationship.

Adult↗
PubMed1990

A CT-based computerized treatment planning system for I-125 stereotactic brain implants.

A computer program has been developed at the University of California, San Francisco, as an aid in planning and evaluating stereotactic brain implants made with 125I seeds. The program allows images of seeds and catheters to be positioned in the target volume revealed by CT. It then generates and displays the resulting isodose distributions. Catheters may be changed interactively until an optimum implant is achieved. From the geometry of a stereotactic implant frame as measured by CT, the program calculates the approach angles of the catheters in the frame coordinate system. After the seeds are implanted, films made with a fiducial marker box can be used to generate true seed positions and hence true isodoses. This paper describes mathematically the geometrical transformations used by the program, and also outlines its many features and options. In its first 2 years of use the program has proved to be a valuable contributor to improved patient care.

Brachytherapy↗
PubMed1990

Prognostic factors for positive surgical staging in patients with Hodgkin's disease.

Staging laparotomy was performed as part of the routine recommended diagnostic evaluation following clinical staging (CS) in 692 patients presenting with supradiaphragmatic Hodgkin's disease (HD). Various clinical factors were analyzed by multivariate analysis for prediction of abdominal involvement. Factors that were statistically significant for predicting disease below the diaphragm included CS III-IV disease (P less than .001), B symptoms (P less than .001), mixed cellularity (MC) or lymphocytic depletion (LD) histology (P = .017), number of supradiaphragmatic sites greater than or equal to 2 (P = .001), male sex (P = 0.034) and age greater than or equal to 40 years (P = .004). Separate analyses were performed for various subgroups of CS IA-IIA, CS IB-IIB, CS IIIA-IVA, and CS IIIB-IVB patients. Upstaging was seen in 0% to 55% of CS I-II patients based on subgroup. Male sex, B symptoms, and number of sites above the diaphragm greater than or equal to 2 all independently predicted for positive surgical staging in CS I-II patients. Sixty-four percent of CS I-II patients who were upstaged had extensive abdominal disease by positive lower abdominal nodes or multiple splenic nodules (greater than or equal to 5). Downstaging (to pathological stage [PS] I-II) was seen in 9% to 68% of patients with CS III-IV disease based on subgrouping. Age greater than or equal to 40, MC or LD histology, and B symptoms all independently predicted for positive surgical staging in CS III-IV patients. Downstaging was more frequently seen in CS IIIA-IVA patients (55%) than in patients who were CS III-IVB (22%). Four subgroups of patients who had a low probability (less than 10%) of stage or treatment change following laparotomy were identified. These included CS IA female patients, CS IA male patients with lymphocyte predominance histology or high neck presentations, and patients with CS IIIB-IVB disease and account for 21% of the study population. Staging laparotomy altered the stage and treatment of a significant number of the remaining 79% patients and should continue to be recommended for this group of patients.

Abdominal Neoplasms↗
PubMed1989

Treatment patterns for schizophrenia in psychiatric hospitals.

This paper analyzes the patterns of clinical treatments prescribed to patients diagnosed with schizophrenia who were admitted to state and county mental hospitals, private for-profit psychiatric hospitals, and private nonprofit psychiatric hospitals in July 1980. Treatment patterns were specified by examining the distribution of treatment types provided to patients over a 3-month period through standard tabular arrays and matrix analysis that holds constant the number of treatment types received by the patients. Data for this study are based on nationwide patient sample surveys and facility enumerations conducted in 1980 by the Survey and Reports Branch, National Institute of Mental Health. Clear differences and similarities emerged among the three types of hospitals in terms of the number and type of treatments provided to patients with schizophrenia. In general, patients with schizophrenia admitted to private psychiatric hospitals received a more comprehensive care regimen (generally inclusive of individual therapy) than similarly diagnosed patients admitted to state and county mental hospitals; private nonprofit psychiatric hospitals had marginally discernible treatment patterns from private for-profit psychiatric hospitals, especially with respect to assignment of group and self-care skill training.

Activities of Daily Living↗
PubMed1989

Auger electron contribution to bromodeoxyuridine cellular radiosensitization.

Halogenated thymidine analogs become incorporated into the DNA of proliferating cells during S-phase and may be used clinically to radiosensitize tumors that are otherwise poorly responsive to radiation. Although radiosensitization has been studied for years, mechanisms of radiosensitization are poorly understood. One possible mechanism involves the release of short range, high-LET, Auger electrons following photoelectric absorption of an X ray by the K-shell of the incorporated halogen. Such absorption occurs only with X ray energies slightly greater than the K-shell binding energy. We report the results of an experiment designed to measure this effect, in which cultured monolayers of Chinese hamster V79 cells, with 32% replacement of thymidine by bromodeoxyuridine (BUdR), were exposed to monoenergetic X rays just below (13.450 KeV) or above (13.490 KeV) the K-edge (13.475 KeV) of bromine. Enhancement ratios calculated in five different ways were slightly increased (3-12%) above the K-edge compared to below. However, only a calculation using a linear-quadratic fit to the data and a surviving fraction of 0.01 demonstrated a statistically significant increased enhancement ratio (12%) above the K-edge. We conclude that Auger electrons produced following photoelectric absorption of X rays by the K-shell of bromine contribute minimally to observed BUdR cellular radiosensitization.

Animals↗
PubMed1989

Short gracilis myocutaneous flaps for vulvovaginal reconstruction after radical pelvic surgery.

The short gracilis myocutaneous flap derives its blood supply from terminal branches of the obturator artery, and the vascular pedicle derived from the medial femoral circumflex artery is sacrificed. Twenty-one short gracilis myocutaneous flaps were used for vulvovaginal reconstructions in 11 patients undergoing radical pelvic surgery: bilateral flaps in nine patients for neovaginal construction after pelvic exenterations, bilateral flaps in one patient for vulvovaginal reconstruction after radical vulvovaginectomy, and a unilateral flap in one patient for vulvovaginal reconstruction after radical vulvectomy with partial vaginectomy. Major complications consisted of bilateral flap necrosis occurring in one patient who had received preoperative irradiation to the vulva and groin combined with chemotherapy. Minor degrees of necrosis (less than 5%) and/or separation of vaginal suture lines occurred in five patients without marked loss of the flaps. Vaginal caliber and depth are excellent in ten patients (91%) after follow-up of 1-22 months. The short gracilis flap is an excellent alternative to the more bulky gracilis flap, which derives its blood supply from perforating branches of the femoral artery. Based on our experience, the short gracilis flap provides adequately vascularized tissue for vulvovaginal reconstruction in patients after radical pelvic surgery, but should not be used in patients who have received extensive groin irradiation.

Adult↗
PubMed1988

Replacement of the macronuclear ribosomal RNA genes of a mutant Tetrahymena using electroporation.

The macronucleus of the ciliate Tetrahymena contains approx. 10(4) ribosomal RNA gene molecules (rDNA) in the form of linear, autonomously replicating palindromes. Previous studies have shown that macronuclear rDNA molecules derived from wild-type (wt) inbred strain C3 out-replicate those derived from wt inbred strain B, in macronuclei initially heterozygous for both, leading to the complete loss of the B rDNA. However, rmm-1, a cis-acting laboratory-induced mutation obtained previously by mutagenesis of inbred strain C3, causes the mutant rmm-1 rDNA to be completely out-replicated by B rDNA. These findings suggest the following hierarchy of replication potential: wt C3 greater than wt B greater than C3-rmm-1. We used electroporation to test whether cells containing only rmm-1 macronuclear rDNA are favorable recipients for transformation with either wt B or C3 donor rDNA molecules. The donor rDNA molecules carried the selectable marker Pmr (paromomycin resistance) located in the coding region of the 17S rRNA. Transformants were obtained, at a frequency greater than 1 in 10(5), by electroporation under a wide range of electrical discharge parameters. The fraction of cells surviving electroporation varied between 2 and greater than 95% in successful experiments. Replacement ('transplacement') of the recipient rDNA was observed, consistent with the prediction that B and C3 rDNA should out-replicate rmm-1 rDNA. These findings are also consistent with the previous conclusion that the differential replication determinants reside in the 5'-nontranscribed spacer of the rDNA.

Animals↗
PubMed1988

Current techniques for chest wall reconstruction: expanded possibilities for treatment.

Myocutaneous flaps and prosthetic materials have greatly facilitated reconstruction after massive chest wall resection. This series includes 112 such procedures. Latissimus dorsi, rectus abdominis, omental, pectoralis major, and contralateral breast flaps were used in 80 patients. Early in the series, 3 flaps were lost because of technical problems. Minor areas of incomplete healing that resolved completely with local wound care occurred in 16 of 80 flaps. Skeletal reconstruction was performed in 82 patients without complication. Marlex mesh was used for flat surfaces, and Marlex mesh with methyl methacrylate was used for the sternum and the curved surface of the lateral chest wall. These results have allowed an expansion of the indications for chest wall resection to include the curative treatment of primary chest wall tumors and palliative treatment for breast cancer patients with osteoradionecrosis, local recurrence (in select patients), chest wall infection, and tumors metastatic to the chest wall.

Adult↗
PubMed1986

Gastrointestinal bleeding in competitive runners.

Competitive runners have been shown to develop previously undescribed clinical conditions, including "runner's anemia." This has been shown to be an iron-deficiency anemia of several etiologies including gastrointestinal bleeding. Although 8-23% of runners have been shown to have guaiac-positive stools after a marathon, the incidence of significant and prolonged bleeding is unknown. We report four cases of competitive runners with iron-deficiency anemia, gastrointestinal bleeding coinciding with running, and no definitive gastrointestinal pathology despite extensive evaluation.

Adult↗
PubMed1986

Longitudinal dichotic listening patterns for aphasic patients. II. Relationship with lesion variables.

Dichotic listening scores and information on lesion size and location were obtained for aphasic patients. All patients had a reduction in dichotic scores at 1 month postonset of symptoms, but some patients returned to normal levels of performance by 6 months postonset. Lesion location was the main determinant of patterns of performance. Right ear scores from the dichotic digit test closely reflected the presence or absence of lesions involving Heschl's gyrus. What appeared to be an effect of lesion volume was confounded by the relationship between increasing lesion volume and a greater likelihood of damage to Heschl's gyrus.

Adult↗
PubMed1986

Edema of the arm as a function of the extent of axillary surgery in patients with stage I-II carcinoma of the breast treated with primary radiotherapy.

Edema of the arm can be a significant complication following treatment of breast cancer. To determine the risk of arm edema and factors associated with this risk in patients treated with primary radiotherapy, we reviewed the records of 475 women with early breast cancer treated between 1968 and 1980. During this period, the use of axillary surgery prior to radiation gradually increased, and all patients received full axillary irradiation until late in the series. Based on the surgeon's report, the extent of axillary surgery was classified as either a sampling, a lower dissection, or a full dissection. Edema of the arm was scored on clinical grounds and ranged from mild hand swelling to an increased arm circumference of 8 cm. At 6 years, the actuarial risk of developing arm edema was 8% for the entire study population. This risk was 13% for 240 patients who had axillary surgery and 4% for 235 patients not undergoing axillary surgery (p = 0.006). For patients undergoing axillary surgery, the risk of arm edema was 37% with full dissection compared to 5% with sampling (p = 0.0003), and 8% with lower dissection (p = 0.03). The risk of arm edema at 6 years was 28% if more than ten nodes were removed, and 9% if one to ten nodes were removed (p = 0.03). However, the extent of axillary dissection was stronger predictor of subsequent edema than was the number of nodes obtained. The role of axillary irradiation could not be evaluated since 91% of patients received axillary irradiation. The use of chemotherapy, the site or size of the primary tumor, clinical nodal status, patient age and weight, type of suture, the use of a drain, and subsequent local or distant failure did not appear to be significant risk factors. We conclude that the combination of full dissection and full axillary irradiation results in an unacceptably high risk of arm edema.

Arm↗
PubMed1985

A large region controls tRNA gene transcription.

We find that tRNA gene transcription is controlled by a region much larger than the previously described internal segments known as A and B boxes. In a Bombyx mori silkworm tRNA2Ala gene, transcriptionally important sequences extend at least from -13 to +146, and thus include sequences both upstream and downstream from the 98 base-pair primary transcription unit. We show that the apparent size of this control region can be manipulated by the conditions used to measure transcription in vitro. Specifically, the use of high concentrations of templates to overcome the effect of an inhibitory substance in crude extracts can make the control region appear smaller. We propose that this finding explains much of the observed variability in the sequence requirements for transcription of different tRNA genes. If so, large size is likely to be a general feature of tRNA gene control regions.

Animals↗
PubMed1984

Rh immune globulin after genetic amniocentesis: impact on pregnancy outcome.

Although Rh immune globulin is commonly given to Rh-negative women undergoing genetic amniocentesis, there is little documentation of the necessity, efficacy, or safety of this policy. In this study, reproductive outcomes in 147 women each receiving 150 micrograms of Rh immune globulin after genetic amniocentesis were compared with those of an equal number of Rh-positive amniocentesis control women. No significant differences were found in the incidence of midtrimester pregnancy loss, mean gestational age at delivery, mean birth weight, or frequency of preterm deliveries (P greater than 0.05 for all parameters). While two antepartum stillbirths occurred in the study group and none in the control population, causes unrelated to Rh immune globulin administration were apparent for both fetal deaths (one multiple congenital anomaly syndrome, one abruptio placentae at 38 weeks). Of the 103 Rh-negative women giving birth to Rh-positive infants, none were overtly sensitized at the time of delivery. It is concluded that second trimester Rh immune globulin administration does not increase the risk of pregnancy loss.

Abortion, Spontaneous↗
PubMed1984

A pulsed Doppler echocardiographic method for calculating pulmonary and systemic blood flow in atrial level shunts: validation studies in animals and initial human experience.

The purpose of this study was to assess the accuracy of a quantitative two-dimensional range-gated Doppler echocardiographic method for estimating systemic and pulmonary flows in an open-chest canine preparation with a variable-sized atrial level shunt mimicking an atrial septal defect. In addition, we also report our initial experience with 10 children who had isolated atrial septal defects and who had pulmonary and systemic flow rations (QP:QS) determined by Doppler echocardiography simultaneously with green dye-shunt calculations in the cardiac catheterization laboratory. Ten mongrel dogs weighing 20 to 30 kg were anesthetized, intubated, and mechanically ventilated. Previously calibrated electromagnetic flow probes were placed around the ascending aorta and main pulmonary artery, and an atrial level shunt was created by inserting one-half inch diameter cannulae into the left and right atrial appendages and connecting both cannulae to 3/4 inch tubing that passed through a previously calibrated extracorporeal mechanical roller pump. This permitted quantitation as well as regulation of shunt size and direction. With each step-by-step variation in shunt magnitude, systemic and pulmonary flows were estimated by Doppler echocardiography and were matched to the simultaneous electromagnetic flowmeter recordings. Doppler-estimated systemic blood flow was obtained by imaging and recording Doppler flow velocities in the ascending aorta with the transducer positioned directly over the vessel. Doppler pulmonary flow was obtained by imaging the main pulmonary artery on the short-axis view and by determining flow velocity with the sample volume placed distal to the pulmonic valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗