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J A Schmidt

Publications and source records attributed to J A Schmidt.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Standardization of nailfold capillary microscopy in routine diagnosis].

BACKGROUND: Nailfold capillary microscopy is scientifically established and recognized as a diagnostic tool in clinical routine. It is, however, practiced in only a few centres. METHODS: But since a more widespread use of the method is to be expected for the near future, a consensus-meeting was held, where all German-speaking clinicians and scientists, involved in capillary microscopy, were invited. Here, the technical procedure and the most important morphological parameters were evaluated and defined according to practical clinical aspects. RESULTS AND CONCLUSION: The main task of the consensus-meeting was to develop a standard evaluation sheet, accompanied by an explanation sheet. This standard evaluation sheet focuses on semiquantitative registration of morphological parameters like density, dilation, avascular fields, perivascular edema, microbleeding, torsion, atypical capillaries and giant capillaries. This standard evaluation sheet is to be validated by determining the inter-observer-variance. Later-on an illustrated practical guideline will be published.

Capillaries↗
PubMed1996

Expression and immunoaffinity purification of human inducible nitric-oxide synthase. Inhibition studies with 2-amino-5,6-dihydro-4H-1,3-thiazine.

Recombinant human inducible nitric-oxide synthase (rH-iNOS) was expressed in the baculovirus system and purified by a novel immunoaffinity column. rH-iNOS and its native counterpart from cytokine-stimulated primary hepatocytes exhibited similar molecular mass of 130 kDa on SDS-polyacrylamide gel electrophoresis, recognition by antipeptide antibodies, specific activities, and IC50 values for inhibitors. The active dimeric form exhibited a specific activity range of 114-260 nmol/min/mg at 37 degrees C and contained 1.15 +/- 0.04 mol of calmodulin/monomer. The enzyme exhibited a Soret lambdamax at 396 nm with a shoulder at 460 nm and contained 0. 28-0.64 mol of heme/monomer. Dithionite reduction under CO yielded an absorbance maximum at 446 nm, indicating a P450-type heme. Imidazole induced a type II difference spectrum, reversible by L-Arg. 2-Amino-5,6-dihydro-4H-1,3-thiazine (ADT) was competitive versus L-Arg (Ki = 22.6 +/- 1.9 nM), reversed the type II difference spectrum induced by imidazole (Kd = 17.7 nM), and altered the CO-ferrous absorbance of rH-iNOS. L-Arg did not perturb the CO-ferrous adduct directly, but it partially reversed the ADT-induced absorbance shift, indicating that both bind similarly to the protein but interact differently with the heme.

Chromatography, High Pressure Liquid↗
PubMed1996

Active-site structure analysis of recombinant human inducible nitric oxide synthase using imidazole.

Nitric oxide synthase catalyzes the pyridine nucleotide-dependent oxidation of L-arginine to nitric oxide and L-citrulline. It is a specialized cytochrome P450 monooxygenase that is sensitive to inhibition by imidazole. Steady-state kinetic studies on recombinant human inducible nitric oxide synthase (rH-iNOS) demonstrate that imidazole and 1-phenylimidazole are competitive and reversible inhibitors versus L-arginine. Structure-activity relationship and pH dependence studies on the inhibition suggest that the neutral form of imidazole may be the preferred species and that the only modifications allowed without the loss of inhibition are at the N-1 position of imidazole. Optical spectrophotometric studies of rH-iNOS with imidazole and 1-phenylimidazole yielded type II difference spectra exhibiting Kd values of 63 +/- 2 and 28 +/- 3 microM, respectively. These values were in good agreement with the steady-state Ki of 95 +/- 10 and 38 +/- 4 microM, respectively, and confirms the site of binding is at the sixth axial ligand of the heme. Imidazole (2.2 mM) also perturbed the Kd of L-arginine from 3.03 +/- 0.45 to 209 +/- 10 microM. The observed increase in the Kd for L-arginine is consistent with imidazole being a competitive inhibitor versus L-arginine. The IC50 values of imidazole and 1-phenylimidazole were lower in the absence of exogenous BH4, and both inhibitors also competitively inhibited the BH4-dependent activation of the enzyme. These data taken together suggest that the L-arginine, dioxygen, and the BH4 binding sites are in close proximity in rH-iNOS. Furthermore, these studies demonstrate the usefulness of imidazole compounds as active site probes for recombinant human iNOS.

Arginine↗
PubMed1996

Gas-phase reactions of glycine, alanine, valine and their N-methyl derivatives with the nitrosonium ion, NO+.

The gas-phase reactions of the nitrosonium ion, NO+ with the amino acids glycine, alanine and valine and their N-methyl derivatives were investigated under chemical ionization mass spectrometric (CIMS) conditions. Two products were observed in all cases: the formation of the iminium ion and the formation of an [M-H]+ ion. The latter product is consistent with a reaction channel involving hydride abstraction by NO+, and was confirmed by (i) examining the Ar+CI mass spectra of the same amino acids under similar source conditions and (ii) examining the unimolecular fragmentation reactions of the [M + H]+ ions of the N-nitroso-N-methyl derivatives of each of the amino acids in a tandem mass spectrometer. Further insights into the reaction of glycine with NO+ were obtained by performing ab initio calculations (at the MP2/6-31G* parallel HF/6-31G* level). These results indicate that four reactions are thermodynamically viable for glycine: (i) hydride abstraction; (ii) iminium ion formation (with concomitant loss of HONO and CO); (iii) diazonium ion formation; and (iv) diazonium ion formation followed by loss of N2. Possible reasons why reactions (iii) and (iv) are not observed are discussed, and comparisons with solution reactivity and the gas-phase reactivity of NO+ are also made.

Alanine↗
PubMed1996

[Diagnosis of floating venous thrombi by spiral CT phlebography].

PURPOSE: Evaluation by means of spiral CT as to whether or not a thrombus in a proximal deep vein of the leg is floating or adherent to the vessel wall. METHODS: Local application of contrast agent into an ipsilateral dorsal foot vein and spiral CT were used to examine 16 consecutive cases with deep venous thrombosis proven at conventional venography; in addition, colour Doppler flow imaging was performed. RESULTS: At conventional venography, 8/16 thrombi appeared to be floating and the remaining 8/16 were adherent to the vessel wall. Spiral-CT showed 15/16 thrombi to be adherent to the vessel wall; the floating thrombus correlated with findings in conventional venography. At colour Doppler flow imaging 3/16 thrombi were considered floating, one of them was discordant to conventional venography. The comparison of conventional venography to spiral-CT demonstrates complete agreement for adherence to vessel wall seen in conventional venography (p = 1,0) and significant discordance in cases with free-floating appearance in conventional venography (p = 0,0002). CONCLUSION: Adherence of thrombi to the wall of the vessel at conventional venography is in agreement with computed tomography. Conventional venography probably overestimates the prevalence of free floating thrombi.

Aged↗
PubMed1996

The role of surgeon-performed ultrasound in patients with possible cardiac wounds.

OBJECTIVE: The authors evaluate surgeon-performed ultrasound in determining the need for operation in patients with possible cardiac wounds. BACKGROUND DATA: Ultrasound quickly is becoming part of the surgeon's diagnostic armamentarium; however, its role for the patient with penetrating injury is less well-defined. Although accurate for the detection of hemopericardium, the lack of immediate availability of the cardiologist to perform the test may delay the diagnosis, adversely affecting patient outcome. To be an effective diagnostic test in trauma centers, ultrasound must be immediately available in the resuscitation area and performed and interpreted by surgeons. METHODS: Surgeons performed pericardial ultrasound examinations on patients with penetrating truncal wounds but no immediate indication for operation. The subcostal view detected hemopericardium, and patients with positive examinations underwent immediate operation by the same surgeon. Vital signs, base deficit, time from examination to operation, operative findings, treatment, and outcome were recorded. RESULTS: During 13 months, 247 patients had surgeon-performed ultrasound. There were 236 true-negative and 10 true-positive results, and no false-negative or false-positive results; however, the pericardial region could not be visualized in one patient. Sensitivity, specificity, and accuracy were 100%; mean examination time was 0.8 minute (246 patients). Of the ten true-positive examinations, three were hypotensive. The mean time (8 patients) from ultrasound to operation was 12.1 minutes; all survived. Operative findings (site of cardiac wounds) were: left ventricle (4), right ventricle (3), right atrium (2), right atrium/superior vena cava (1), and right atrium/inferior vena cava (1). CONCLUSIONS: Surgeon-performed ultrasound is a rapid and accurate technique for diagnosing hemopericardium. Delay times from admission to operating room are minimized when the surgeon performs the ultrasound examination.

Adolescent↗
PubMed1996

Ultrasound training during ATLS: an early start for surgical interns.

OBJECTIVES: Determine if: (1) surgical interns could learn essential ultrasound principles of the focused assessment for the sonographic examination of the trauma patient (FAST) during Advanced Trauma Life Support (ATLS), and (2) swine are adequate models for learning the FAST. DESIGN: Lecture, videotape, pre/posttests, and practical examination. METHODOLOGY: Day 1: Survey, pretest, lecture, and videotape. Day 2: Three swine, used in ATLS, had diagnostic peritoneal lavage catheters reinserted to infuse fluid and produce "positive" ultrasound examinations. Two fresh swine were "negatives"; however, all five swine were draped similarly to disguise interventions. Interns were tested individually by surgeon-sonographers to determine whether the ultrasound image was "positive" or "negative." Posttests were completed while surgeons performed postmortem examinations on two swine. STATISTICS: Paired Student's t test and Wilcoxon Rank Sum test. RESULTS: Survey (5 min): 48% had exposure to ultrasound. Relationship of test scores showed no significant difference (p = 0.46 to 0.91) between interns with and without ultrasound experience. Tests (30 min): Mean pre- and posttests scores = 65.6 and 90.8, respectively (p < 0.001). Practical examination (140 min): Mean score = 89.6. Postmortem examinations: Left hepatic lobe partially obscured the spleen. CONCLUSIONS: (1) Surgical interns can learn essential ultrasound principles of the FAST during ATLS (2) Swine are feasible models for learning the FAST.

Animals↗
PubMed1996

Intravital microscopy and capillaroscopically guided nail fold biopsy in scleroderma.

OBJECTIVES: To describe the frequency, extent, and nature of microvascular lesions in patients with scleroderma by means of capillaroscopy and capillaroscopically guided nail fold biopsy, and to determine the diagnostic value of the two methods and the pathophysiological significance of the lesions described. METHODS: A cohort study was made of 24 consecutive patients with scleroderma and 10 healthy controls, using standardised clinical, serological, capillaroscopic, and histological (nail fold biopsy) techniques. RESULTS: All patients with scleroderma had distinct lesions of the microvascular system. Capillaroscopy revealed more than 90% of the patients to have the typical scleroderma pattern. Histologically, these changes most frequently consisted of splitting of the basal lamina, broadening of the perivascular connective tissue, perivascular round cell infiltrations, and immunoglobulin deposits (each in 60-75% of the patients). Electron microscopy was the most sensitive method of histological examination, detecting abnormalities in 87.5% of patients; with light microscopy and immunohistochemical techniques, abnormalities were revealed less frequently (83.3% and 75%, respectively). In contrast, normal findings were observed in most of the healthy controls: capillaroscopy = 90%; histology = 80%. CONCLUSIONS: Microvascular lesions are a predominant feature in scleroderma and seem to have a central pathogenetic role in the disease. Capillaroscopy is able to identify this microangiopathy noninvasively, and capillaroscopically guided nail fold biopsy can detect the frequency and nature of the underlying ultrastructural changes. This may therefore be a useful tool in describing the pathogenetic role of the microvascular system in scleroderma.

Adult↗
PubMed1996

Acute effects of therapeutic ultrasound delivered at varying parameters on the blood flow velocity in a muscular distribution artery.

Therapeutic modalities that alter hemodynamic parameters may have a dramatic impact on the viability of living tissues. The purpose of the current study was to investigate the response of blood flow velocity to various treatment parameters of therapeutic ultrasound. Twenty healthy volunteers attended six randomly selected, 15-minute treatment sessions of the following parameters: Tx-1 = 1.0 MHz at 1.5 W/cm2, Tx-2 = 1.0 MHz at 1.0 W/cm2; Tx-3 = 3.0 MHz at 1.2 W/cm2; Tx-4 = 3.0 MHz at 1.0 W/cm2, Tx-5 = sham; and Tx-6 = control. Ultrasound was applied to a circular area over the triceps surae muscle mass. Blood flow velocity in the popliteal artery was assessed after 5, 10, and 15 minutes of ultrasound and at two posttreatment intervals via a dual frequency, bidirectional ultrasound Doppler. A two-factor analysis of variance (p < or = 0.05) with repeated measures for treatment and time was performed on the data. Groups Tx-1 and Tx-2 showed significant increases in blood flow velocity when compared with the control and all other groups. The sham group showed significant increases in blood flow velocity when compared with the control group. Group Tx-3 and Tx-4 showed no significant change when compared with the sham condition. The results of the current study indicate that 1.0 MHz ultrasound delivered at 1.0 and 1.5 W/cm2 to the triceps surae musculature as described in the present study can increase the blood flow velocity in the popliteal artery.

Adult↗
PubMed1995

Human IL-1 beta processing and secretion in recombinant baculovirus-infected Sf9 cells is blocked by the cowpox virus serpin crmA.

Biologically active, mature IL-1 beta (mIL-1 beta) is released from activated monocytes after proteolytic processing from an inactive precursor (pIL-1 beta). IL-1 beta converting enzyme (ICE), the first member of a newly discovered family of cysteine proteinases, is required for this processing event. The cleaved cytokine is released from monocytes by an unknown mechanism which does not employ a standard hydrophobic signal sequence. As in mammalian fibroblasts, insect Sf9 cells do not normally process or secrete human IL-1 beta. The expression of active ICE enables Sf9 cells to process 31-kDa pIL-1 beta correctly at Asp27 and Asp116, and to export 17.5-kDa mIL-1 beta. The recombinant heterodimeric human enzyme purified from Sf9 cells possesses a sp. act. of 2.9 +/- 0.5 x 10(6) U/mg and is indistinguishable from native ICE with regard to its subunit composition and catalytic properties. In this system, co-expression of the cowpox virus crmA gene, an extremely potent serpin inhibitor of ICE (Ki < 7 pM), inhibits ICE activation completely and blocks pIL-1 beta processing and mIL-1 beta secretion by approximately 95%. The results indicate that ICE, in addition to its processing function, facilitates the transport of IL-1 beta across the plasma membrane.

Amino Acid Sequence↗
PubMed1995

Assessing the interpersonal transaction cycle: convergence of action and reaction interpersonal circumplex measures.

Contemporary interpersonal theory uses 2 models to represent the process and content of interpersonal transactions. The interpersonal transaction cycle is a dynamic model demonstrating the interaction between the overt behaviors and the covert intrapsychic experiences of 2 interacting individuals in action-reaction event chains. The interpersonal circle is a static model codifying individual differences across various interpersonal content domains (e.g., traits, acts, problems, impacts). The present study used 150 pairs of undergraduates to demonstrate cross-observer structural convergence of 2 separate interpersonal circumplex inventories measuring the "action" and "reaction" components of the transaction cycle, providing evidence that both components of the cycle can be captured by existing circumplex measures, and allowing researchers to proceed on to more comprehensive tests of interpersonal theory.

Adult↗
PubMed1995

A prospective study of surgeon-performed ultrasound as the primary adjuvant modality for injured patient assessment.

Ultrasound diagnostic imaging, having been used in Germany in the trauma setting for more than 15 years, has unique qualities that give it distinct advantages over other tests (DPL, CT), and is gradually gaining acceptance by surgeons in the United States. In this prospective study, experienced surgeon sonographers successfully used ultrasound as the primary adjuvant modality to detect hemoperitoneum and pericardial effusion in injured patients. The ultrasound evaluations of 371 patients demonstrated that in 65 patients with significant injuries, ultrasound detected 53, that is, had an 81.5% sensitivity and 99.7% specificity. They conclude that ultrasound should be the primary adjuvant instrument for the evaluation of injured patients because it is rapid, accurate, and is potentially cost-effective.

Adolescent↗
PubMed1995

The evaluation of a two-tier trauma response system at a major trauma center: is it cost effective and safe?

OBJECTIVE: To determine the efficacy and safety of a two-tier trauma response, using prehospital criteria for matching trauma center assets with severity of injury. DESIGN: A prospective iterative study on a consecutive sample of patients to test the hypothesis. MATERIAL AND METHODS: Criteria were developed whereby in-hospital response was determined by information provided by prehospital personnel. Two modifications of these criteria were introduced at 6 and 9 months. Triage and response accuracy were evaluated using outcome variables. Cost savings were estimated using differences between the full and modified teams. Chi-squared analysis was used. MEASUREMENTS AND MAIN RESULTS: Of 1,479 patients evaluated over a 9-month period, 682 (46%) received a full trauma team response, and a modified trauma team responded to 794 (54%). When compared with final designation by outcome variables, the sensitivity, specificity, and accuracy were significantly improved after the first modification of criteria. After the second modification, there was no significant improvement; however, the number of undertriaged patients increased significantly. Estimated cost savings were about $178,000 over the 9-month period. CONCLUSIONS: Utilization of a two-tier response to trauma patients is effective, safe, and results in substantial cost savings.

Adolescent↗