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D Johnson

Publications and source records attributed to D Johnson.

At least 361 records · Page 20Linked to original sources
PubMed1994

Crystallization and preliminary X-ray diffraction studies of the soluble 14 kDa beta-galactoside-binding lectin from bovine heart.

The soluble 14 kDa beta-galactoside-binding lectin from bovine heart, a member of the S-type lectin family, has been crystallized in a form suitable for X-ray diffraction analysis. The crystals, in the absence of a saccharide ligand, diffract beyond 2.5 A resolution. They are obtained from polyethylene glycol 6000 at pH 6.0. Crystals grow as monoclinic plates, space group P2(1), with cell dimensions: a = 35.47 A, b = 64.33 A, c = 58.78 A and beta = 91.7 degrees. The asymmetric unit contains two molecules related by a 2-fold non-crystallographic axis. Two lectin monomers in the asymmetric unit give a Vm of 2.4 A3/Da, i.e. a solvent content of approximately 50%. The complex of lectin with the saccharide ligand, N-acetyllactosamine, crystallizes in the space group P2(1)2(1)2 with cell dimensions: a = 63.55 A, b = 82.13 A and c = 62.39 A. Crystals of this complex diffract beyond 2.0 A resolution. Two complexes in the asymmetric unit lead to a Vm value of 2.8 A3/Da (57% solvent).

Amino Sugars↗
PubMed1994

Elevation of serum free triiodothyronine, total triiodothyronine, thyroxine-binding globulin, and total thyroxine levels in combat-related posttraumatic stress disorder.

BACKGROUND: This study was designed to assess both central and peripheral aspects of thyroid function in combat-related posttraumatic stress disorder (PTSD), with the particular purpose of finding a mechanistic explanation for an imbalance between serum levels of free thyroxine (T4) and total T4 previously observed in pilot work. METHODS: A total of 96 male combat veterans with PTSD diagnosed by DSM-III-R (72 from the West Haven, Conn, Veterans Affairs Medical Center and 24 from the Menlo Park, Calif, Veterans Affairs Medical Center) were compared with 24 male control subjects. One or more serum samples were analyzed by radioimmunoassays for levels of total T4, free T4, total triiodothyronine (T3), free T3, T4-binding globulin, and thyrotropin. RESULTS: The pilot observation of moderately elevated total T4 levels with no elevation in free T4 levels in patients with PTSD was confirmed, suggesting the hypotheses that (1) there may be an increased peripheral conversion of free T4 by deiodination to T3 or (2) there may be an increased binding of T4 secondary to elevated T4-binding globulin levels. Our findings support both hypotheses. The PTSD groups all showed a marked and sustained elevation in levels of both total T3 and free T3, as well as elevated T3/T4 ratios, supporting the increased T3 conversion hypothesis. The PTSD groups also showed a marked and sustained increase in T4-binding globulin levels, supporting the increased binding hypothesis. Thyrotropin levels did not differ between PTSD and control groups. CONCLUSIONS: These findings demonstrate an unusual pattern of thyroid alterations, featuring substantial elevations in total T3, free T3, and T4-binding globulin levels, in combat-related PTSD that differs from established endocrinopathies, such as classic hyperthyroidism, T3 thyrotoxicosis, or chronic T4-binding globulin elevation.

Adult↗
PubMed1994

Lazaroid pretreatment preserves gas exchange in endotoxin-treated dogs.

PURPOSE: The lazaroids are a new class of potent free-radical scavengers. We tested whether U-74389G, a lazaroid, could attenuate some of the adverse cardiopulmonary effects of sepsis. METHODS: Dogs were randomized to receive either 10 mg/kg U-74389G (n = 10), or a saline control (n = 11). After baseline measurements of hemodynamics and gas exchange, they were then randomized to receive either 0.2 mg/kg endotoxin or a saline infusion. Measurements of hemodynamics and gas exchange were repeated. The study was concluded 70 minutes after endotoxin infusion and the lungs were then removed for histologic evaluation. RESULTS: In endotoxin-treated control animals, PO2 decreased (278 +/- 123 mm Hg to 67 +/- 13 mm Hg, P < .05) and intrapulmonary shunt increased (12.9% +/- 1.1% to 28.2% +/- 11.4%, P < .05) after endotoxin. Pretreatment with U-74389G attenuated the decrease in PO2 (476 +/- 61 mm Hg to 226 +/- 143) and the increase in intrapulmonary shunt (12.6% +/- 6.1% to 14.3% +/- 6.8%) observed after endotoxin. The extent of lung injury and systemic hemodynamics were similar between control or U-74389G-treated dogs. CONCLUSIONS: A free-radical-scavenger can attenuate the gas exchange defect commonly associated with endotoxin but it does not improve the derangement of systemic hemodynamics.

Analysis of Variance↗
PubMed1994

Characteristics of teens tested for HIV in a metropolitan area.

PURPOSE: This article describes the status of HIV infection in an adolescent population attending publicly supported HIV testing clinics in Houston. METHODS: Records were reviewed of 4017 teenagers receiving HIV counseling and testing services over a period of three years (January 1990 to December 1992). We analyzed demographic characteristics, risk exposure groups, results of HIV antibody testing, and post-test counseling return rates. RESULTS: An overall seroprevalence rate of 10.2 per 1000 was observed, with the majority of cases seen among black females. Forty-nine percent of teens with the virus failed to acknowledge a risk factor, but of those who did, male-to-male sexual contact was the most frequently reported. None who tested positive reported injected drug use. The majority of teens tested never returned to obtain their test results and post-test counseling. CONCLUSIONS: In order to reinforce preventive behavior, institutional and other barriers should be examined and priority given to contacting both seropositive and high-risk clients who have sought testing. Interventions that encourage condom use or address sexual behavior may be more beneficial to teens than those that simply focus on drug use.

AIDS Serodiagnosis↗
PubMed1994

Observations concerning the microbial etiology of acute salpingitis.

OBJECTIVES: The specific aims of this study were (1) to describe the microbiologic characteristics of patients with acute salpingitis and (2) to determine the incidence of bacterial vaginosis in patients with acute salpingitis and whether bacterial vaginosis microorganisms were common upper-genital-tract isolates in these patients. STUDY DESIGN: Women with pelvic inflammatory disease underwent laparoscopy to confirm the diagnosis of acute salpingitis and for culture of the fallopian tubes and cul-de-sac. Endometrial and minute fimbrial biopsies were performed, and specimens were evaluated for evidence of inflammation. Bacterial vaginosis was diagnosed by vaginal Gram stain. RESULTS: Eighty-four patients had visually confirmed acute salpingitis. Neisseria gonorrhoeae or Chlamydia trachomatis was isolated from 65 (77.4%) patients. Vaginal microorganisms were isolated from the endometrium in 16 (31.4%) of 51 cases and from the cul-de-sac in 12 (14.3%) of 84 cases. Bacterial vaginosis was present in 61.8% of patients with acute salpingitis, and 100% of anaerobes isolated from the upper genital tract of patients with acute salpingitis were bacterial vaginosis microorganisms. These anaerobes were isolated from the upper genital tract in the absence of a concurrent gonococcal, chlamydial, or Haemophilus influenzae infection in only two cases. CONCLUSIONS: The initiation of acute salpingitis is predominantly due to the ascending spread of sexually transmitted microorganisms. Bacterial vaginosis is a common concurrent disorder of women with acute salpingitis, and bacterial vaginosis microorganisms are commonly isolated from the upper genital tracts of patients with pelvic inflammatory disease.

Acute Disease↗
PubMed1994

Characterization of membrane proteins exported from Plasmodium falciparum into the host erythrocyte.

Plasmodium falciparum is an intracellular parasite of the red blood cell. During development it exports proteins which are transported to specific locations within the host erythrocyte. We have begun to identify and characterize exported membrane proteins of P. falciparum in order to obtain specific marker molecules for the study of the mechanisms involved in the distribution of parasite-derived proteins within the host cell. In this report we describe the characterization of a 35 kDa protein which is recognized by a monoclonal antibody. The protein is tightly associated with membranes isolated from infected erythrocytes; it is resistant to extraction with alkali and soluble after treatment with detergents. It is located at the membrane of the parasitophorous vacuole and in membrane-bound compartments which appear in the cytoplasm of the infected erythrocyte. The protein co-localizes with the previously described exported protein-1 (exp-1). Considering its localization and physical similarities to exp-1, we name the 35 kDa protein the exported protein-2 (exp-2).

Animals↗
PubMed1994

Antibiotic-associated pseudomembranous enteritis due to Clostridium difficile.

Although pseudomembranous colitis is relatively common following antibiotic exposure, there have been few reported cases of pseudomembrane formation involving the small intestine. Herein we report a case of pseudomembranous enteritis of the small and large intestine that occurred after antibiotic exposure. The etiologic organism appears to be Clostridium difficile, as evidenced by the characteristic pseudomembranous lesions and a positive ELISA for toxin A in an ileal tissue specimen.

Aged↗
PubMed1994

Sexual differentiation and preimplantation cell growth.

Growth rates of human preimplantation embryos fertilized in vitro were assessed and compared to the sex of the pregnancy outcome. The likelihood of a liveborn male was significantly greater than that of a female if the mean number of cells/embryo was four or greater at the scheduled time of transfer (odds ratio of 6:1). This finding suggested that the Y chromosome expresses factors which influence embryonic growth rates immediately after fertilization.

Blastocyst↗
PubMed1994

The effects of electronic article surveillance systems on permanent cardiac pacemakers: an in vitro study.

UNLABELLED: Five Siemens Pacesetter cardiac pacemakers (PM) were subjected to in vitro testing with six different electronic article surveillance (EAS) devices. The PMs consisted of polarity programmable, dedicated bipolar, and dedicated unipolar types. EAS equipment included UHF, RF, Magnetic, and Magnetoacoustic (MA) devices from two manufacturers. Prior to testing, each PM was interrogated and normal operation confirmed. Each PM was attached to a heart simulator via an eight foot cable and then subjected to testing within the EAS field. The PMs were passed through the field in two axes, positioned stationary within the field, and, worst case (WC), placed directly against the transmitter. During testing the ECG was observed and PM behavior recorded. In one PM (Synchrony III), Event Records, and Event Histograms were utilized. At the conclusion of testing with each EAS device the PM was evaluated for normal operation. RESULTS: No PM was reprogrammed by the EAS devices. UHF produced no effect on the PMs. RF produced noise response in one unipolar PM while in the WC position. High frequency and multifrequency magnetic units produced positive results only in the WC position. Unipolar PMs were affected more often than bipolar. MA and older magnetic EAS units produced more positive responses than newer lower power devices. One incident of close coupled (400 msec) ventricular pacing was seen with the MA EAS unit. CONCLUSIONS: UHF, RF, high frequency, and dual frequency magnetic EAS produced few effects during in vitro testing. Except with the MA and low frequency magnetic devices, positive results occurred only in WC conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography↗
PubMed1994

Effects of hypericum extract LI 160 compared with maprotiline on resting EEG and evoked potentials in 24 volunteers.

In a randomized double-blind study, the effect of hypericum extract was compared to that of maprotiline in 24 healthy volunteers. The investigations included measurements of resting EEG as well as visual and acoustic evoked potentials. In resting EEGs, both medications revealed oppositely directed changes in the theta frequencies, and mainly similarly directed changes in alpha and beta frequencies. Measurements of evoked potentials in the theta and beta frequencies supported these results. The results indicate improved cognitive functions mainly with the treatment of hypericum extract.

Adolescent↗
PubMed1994

Cisplatin plus doxorubicin plus cyclophosphamide in metastatic or recurrent thymoma: final results of an intergroup trial. The Eastern Cooperative Oncology Group, Southwest Oncology Group, and Southeastern Cancer Study Group.

PURPOSE: The purpose of this study was to evaluate the impact of cisplatin, doxorubicin, and cyclophosphamide (PAC) in patients with advanced thymoma with respect to response rate, duration of remission, and overall survival. PATIENTS AND METHODS: Assessable patients with thymoma (n = 29) or thymic carcinoma (n = 1) with metastatic or locally progressive recurrent disease following radiotherapy were treated with intravenous cisplatin (50 mg/m2), doxorubicin (50 mg/m2), and cyclophosphamide (500 mg/m2) with normal saline hydration. Courses were repeated every 3 weeks for a maximum of eight cycles of therapy. RESULTS: Toxicity, which was primarily hematologic, was mild, with only one patient developing a fever associated with neutropenia. Three complete responses (CRs) and 12 partial responses (PRs) were observed (CR+PR rate, 50%; 95% confidence interval, 31.3% to 68.7%). Ten patients had stable disease. The median duration of response was 11.8 months (range, 0.9 to 70.5+), the time to treatment failure 18.4 months (range, 0.8 to 91.9+), and median survival time 37.7 months (range, 2 to 91.9+). CONCLUSION: This trial demonstrates that objective response rates and prolonged survival can be achieved in patients with advanced thymoma.

Adult↗
PubMed1994

Movement of axoplasmic organelles on actin filaments assembled on acrosomal processes: evidence for a barbed-end-directed organelle motor.

The directionality of the actin-dependent motors on squid axoplasmic organelles was determined using actin filaments assembled on the barbed ends of acrosomal processes. Acrosomal processes were isolated from Limulus polyphemus sperm and incubated in monomeric actin under conditions that promoted barbed end assembly only. Newly assembled actin was stabilized and stained with rhodamine-phalloidin and the presence of filaments at the barbed ends of the acrosomal processes was verified by fluorescence microscopy and negative contrast electron microscopy. Axoplasmic organelles that dissociated from extruded axoplasm were observed by video microscopy to move along the newly assembled actin filaments at an average velocity of 1.1 +/- 0.3 microns/second. All organelles moved in the direction away from the acrosomal fragment and towards the tip of the actin filaments. Therefore, the actin-dependent organelle motor on axoplasmic organelles is a barbed-end-directed motor like other myosins analyzed. These findings support the conclusions that axoplasmic organelles are driven by a myosin-like motor along actin filaments and that these filaments as well as microtubules function in fast axonal transport.

Acrosome↗
PubMed1994

Stress, depression, substance abuse, and racism.

Many studies have focused on the special needs of American Indian populations. Some of these studies have special impact on Indian veterans. These can be grouped for consideration around cultural and personal identity problems. These problems are multifaceted and interacting. They bear directly on the community and individual self-esteem. The four major points of these problems are stress, depression, alcohol/drug dependence, and racism.

Adult↗