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Biomedical subjects

K G Schmidt

Publications and source records attributed to K G Schmidt.

At least 19 recordsLinked to original sources
PubMed2006

Development and application of a specially designed heating system for temperature-programmed high-performance liquid chromatography using subcritical water as the mobile phase.

A specially designed heating system for temperature-programmed HPLC was developed based on experimental measurements of eluent temperature inside a stainless steel capillary using a very thin thermocouple. The heating system can be operated at temperatures up to 225 degrees C and consists of a preheating, a column heating and a cooling unit. Fast cycle times after a temperature gradient can be realized by an internal silicone oil bath which cools down the preheating and column heating unit. Long-term thermal stability of a polybutadiene-coated zirconium dioxide column has been evaluated using a tubular oven in which the column was placed. The packing material was stable after 50h of operation at 185 degrees C. A mixture containing four steroids was separated at ambient conditions using a mobile phase of 25% acetonitrile:75% deionized water and a mobile phase of pure deionized water at 185 degrees C using the specially designed heating system and the PBD column. Analysis time could be drastically reduced from 17 min at ambient conditions and a flow rate of 1 mL/min to only 1.2 min at 185 degrees C and a flow rate of 5 mL/min. At these extreme conditions, no thermal mismatch was observed and peaks were not distorted, thus underlining the performance of the developed heating system. Temperature programming was performed by separating cytostatic and antibiotic drugs with a temperature gradient using only water as the mobile phase. In contrast to an isocratic elution of this mixture at room temperature, overall analysis time could be reduced two-fold from 20 to 10 min.

Chromatography, High Pressure Liquid↗
PubMed2005

Acute hemorrhagic pericarditis in a child with pneumonia due to Chlamydophila pneumoniae.

Chlamydophila pneumoniae is mainly responsible for respiratory tract infections but has also been associated with endocarditis and myocarditis. We report a case of pneumonia in a child with hemorrhagic pericardial effusion with a positive result by a new C. pneumoniae TaqMan PCR, suggesting a pericardial inflammation directly induced by C. pneumoniae. C. pneumoniae should be suspected in patients with community-acquired pneumonia and concurrent pericarditis. Empirical treatment with azithromycin seems feasible.

Acute Disease↗
PubMed2004

Severe pulmonary regurgitation late after total repair of tetralogy of Fallot: surgical considerations.

BACKGROUND: After total repair of tetralogy of Fallot (TOF-R) with transannular patching (TAP), severe pulmonary regurgitation (PR) is reported to develop in up to 30% of patients at a follow-up of 20 years, and 10-15% or more need pulmonary valve replacement (PVR). In this study, time-related progression of PR and right ventricular (RV) dilatation, and functional recovery of the RV after PVR are analyzed, and the possible causes of PR and timing of PVR are discussed. METHODS: Eighteen patients, who late after TOF-R with TAP underwent PVR for severe PR, were chosen for the study. NYHA class, QRS duration, RV dilatation index (RVDI = RVEDD/LVEDD), and RV-distal pulmonary artery (PA) peak systolic gradient were reviewed and retrospectively analyzed. RESULTS: TOF-R was performed at a mean age of 5.1 +/- 3.9 years (range: 0.6-12.8 years); the mean time interval from TOF-R to PR grade 3 onset was 11.8 +/- 7.0 years (range: 3.3-27.4 years), and from TOF-R to PVR was 18.5 +/- 7.8 years (range: 8.7-37.1 years). At PVR, 11 patients were in NYHA class II-III, all patients had severe PR (grade 3/3) and severe RV enlargement, 4 patients had ventricular arrhythmias, 7 patients significant distal pulmonary artery stenosis, and 2 patients small nonrelevant residual VSD. The mean preoperative RVDI (normal: 0.5) was 0.99 +/- 0.14 (range: 0.75-1.3), the mean QRS duration 170 +/- 24 ms (140-220 ms), and the mean RV-distal PA peak systolic pressure gradient 33.3 +/- 19.0 mmHg (range: 10-60 mmHg). Patients aged at TOF-R> 5 years had considerably longer redo-free intervals than their younger counterparts: mean 23.1 years (range 8.7-37.1 years) vs 14.8 years (range: 9.3-21.2 years), respectively. The redo-free intervals and the duration of severe PR correlated inversely with the RV-PA gradient. At a mean follow-up of 1.3 years (2 weeks-5 years), the mean RVDI decreased from 0.99 +/- 0.14 to 0.69 +/- 0.15, the mean validity class improved from 2.5 to 1.1. One patient died. CONCLUSIONS: After TOF-R with TAP, the progression of PR has very individual dynamics, resulting in extremely varying redo-free intervals. Concomitant pulmonary stenosis seems to exaggerate progression of PR. PVR results in effective reduction of diastolic dimensions of severely dilated RV and in improvement of validity class. Referred PVR in no-risk cases seems to be justified.

Cardiac Surgical Procedures↗
PubMed2003

Pathological changes of the myocardium in patients after atrial repair for transposition of the great arteries: a possible explanation for left ventricular dysfunction after secondary arterial switch.

BACKGROUND: Patients with transposition of the great arteries who underwent an atrial repair in infancy are likely to develop right ventricular dysfunction later in life. For these patients a two-stage arterial switch operation has been advocated by some groups but mortality even from the initial pulmonary banding procedure for retraining the left ventricle has been reported to be considerable. We asked whether pathological alterations of the left ventricular myocardium could explain for the failure of the left ventricle observed in patients after two-stage arterial switch operations. METHODS: Twelve patients aged 16.9 [8-25.4] years (median [range]) with transposition of the great arteries after atrial repair in infancy were enrolled. Median follow-up interval was 15.8 [7.8-22.1] years. Measurements of right and left ventricular systolic function were performed by echocardiography. In addition all patients underwent cardiac catheterization. Endomyocardial biopsies were taken from the right and left ventricle and examined histopathologically. RESULTS: Two out of twelve patients showed mildly reduced systolic right ventricular function. Systolic function of the left ventricle was normal in all patients on echocardiography but six out of twelve patients showed clusters of fibrous and fatty degeneration on biopsy specimens obtained from the left ventricle. CONCLUSION: We conclude that degenerative left ventricular myocardial changes could serve as an explanation for left ventricular failing when retraining the left ventricle during two-stage arterial switch operations.

Adolescent↗
PubMed2002

[Aortico-left ventricular tunnel: a rare differential diagnosis of congenital aortic insufficiency].

Aortico-left ventricular tunnel (ALVT) is a rare congenital cardiac malformation that presents with cardiac failure and clinical findings of severe aortic regurgitation in early infancy. The diagnosis should be made with 2-D echocardiography by demonstrating an abnormal tunnel-like structure that connects the ascending aorta with the left ventricle. Up to 45% of the patients may have associated cardiac defects, and the development of this bizarre lesion is still unclear. In contrast to congenital aortic regurgitation, ALVT has a better prognosis. Early surgical intervention is curative, but non-operated children die because of heart failure. Therefore, knowledge of this rare cardiac malformation is mandatory if an infant presents with findings of aortic regurgitation.

Aorta↗
PubMed2001

Cytogenetic aberrations in adult acute lymphocytic leukemia: optimal technique may influence the results.

The aim of the present study was to analyse the distribution of cytogenetic aberrations in adult ALL in a population based material and compare the results with literature data. Forty-one patients were diagnosed during a 12-year period. The age varied between 14 and 82 (mean 37, median 32). Thirty-two patients were cytogenetically investigated and in all cases analysable metaphases were obtained (range 10-29, mean 24, median 25, success rate: 100%). Nine (28%) patients had a T-phenotype and 23 (72%) had a pre-B phenotype. High hyperdiploidy was found in four patients (13%). Hypodiploidy was found in 5 patients (16%), 10 (31%) had a pseudodiploid chromosome mode and four (13%) showed low hyperdiploidy (chromosome mode 47-51). Chromosomes 10 and 18 were most frequently involved in numerical aberrations. Structural aberrations most frequently involved chromosomes 6, 9 and 22. t(9;22) was seen in six cases (19%), del(6q) in five cases (16%) and der(9p) in five cases (16%). High hyperdiploid clones, which are associated with a favorable prognosis, were found with the same frequency as in other studies. The frequency of t(9;22) was 19% in our study, others have found frequencies between 11% and 30%. Compared to previously published studies our patients with t(9;22) were younger. Furthermore, those with del(6q) were older, showing a median age equivalent to the patient group as a whole. The differences between our data and previously published studies may be explained by population-based derived data and especially by an optimal technique in obtaining metaphases.

Adolescent↗
PubMed2001

[Ocular hemodynamics and visual field in glaucoma treated with dorzolamide].

OBJECTIVE: It has been shown that oral carbonic anhydrase inhibitors improve visual function in glaucoma. Furthermore topical dorzolamide might improve ocular hemodynamics, as was demonstrated previously. This study was undertaken to evaluate whether topical dorzolamide affects visual function and ocular hemodynamics in glaucoma. METHODS: In a retrospective, open clinical trial, dorzolamide eye drops were administered to 28 patients with confirmed primary open angle glaucoma (POAG) in both eyes, 3 times daily for a mean follow up of 9 months. One eye was randomly chosen for evaluation. IOP, blood pressure, heart rate, pulsatile ocular blood flow (POBF) and Humphrey 30-2 visual fields were measured at baseline and after the start of the therapy. POBF was determined by pneumotonography. For statistical analysis the Wilcoxon-matched-paired test and the Bonferoni-Holm adjustment were used. RESULTS: In dorzolamide-treated patients the IOP dropped from 18 mmHg to 15.5 mmHg after 9 months therapy (p < 0.01) and the visual field improved significantly by 18% (p < 0.05). A statistically significant change was found for POBF from 543 microliters/min to 675 microliters/min (p < 0.05). CONCLUSIONS: The results showed the expected drop in intraocular pressure. Visual function and pulsatile ocular blood flow improved significantly which might be explained by an analogous, vasodilatory effect as was observed in orally applied carbonic anhydrase inhibitors.

Aged↗
PubMed2001

[Thrombolysis of prosthetic heart valve thrombosis using recombinant tissue plasminogen activator (rt-PA) in infancy and childhood].

Thrombotic obstruction of a mechanical cardiac valve prosthesis requires urgent therapy. We report on the treatment of prosthetic valve thrombosis with recombinant tissue plasminogen activator (rt-PA) in three children at the age of 4, 10 and 18 months, in whom a St. Jude Medical prosthesis had been placed at the atrioventricular valve level 2 to 6 weeks earlier. The initial rt-PA dose was 0.4 mg/kg given over 15 min and followed by a continuous daily infusion of 1.6 to 2.0 mg/kg. In addition the patients received heparin (200 U/kg/d). Thrombolytic therapy was administered for a range of 4 to 28 days. The therapy was successful in the first case. The second child had four recurrent events of prosthetic valve thrombosis and the thrombolytic therapy was successful three times. However, the prosthesis had to be finally replaced. In the third case the thrombolytic therapy was only partially successful due to an organized thrombus requiring prosthesis replacement.

Age Factors↗
PubMed2001

Ischemic small bowel strictures in a case of incomplete Kawasaki disease.

The authors describe an atypical case of Kawasaki disease in a 9-month-old girl who presented with fever, coronary artery aneurysms, and acquired ischemic stricture of the proximal jejunum. Histology of the surgical specimen was consistent with mesenteric vasculitis. The infant had only some of the typical clinical signs of Kawasaki disease, suggesting that an atypical or incomplete form of the disease was present. To the best of the authors' knowledge this is only the third case to be reported of incomplete Kawasaki disease associated with ischemic bowel stricture. J Pediatr Surg 36:648-650.

Biopsy, Needle↗
PubMed2001

Occlusion of interatrial communications with the Amplatzer device: experience in 48 consecutive patients.

Both secundum atrial septal defect (ASD) and patent foramen ovale (PFO) have been closed interventionally using several different occluding devices. At a single institution we strived for interventional occlusion of interatrial communications using the Amplatzer device exclusively. During a study period of 22 months, we studied 48 patients ranging in age from 1 to 48 years with an ASD (n = 45) or a PFO (n = 3). Successful implantation of an Amplatzer device was possible in 92% of the patients, and 95% of these patients had a complete early closure of their defect. There were no complications related to the procedure. We conclude that interventional closure of interatrial communications with the Amplatzer device is feasible and safe for selected patients.

Adolescent↗
PubMed2001

Ocular pulse amplitude is reduced in patients with advanced retinitis pigmentosa.

BACKGROUND/AIMS: The choroid, a low resistance vascular structure carrying 85% of the ocular blood flow, provides nourishment to and removal of potential toxic waste products from the adjacent non-vascularised outer layers of the retina, macula, and optic disc regions. Choroidal perfusion may be reduced in retinitis pigmentosa (RP) and might contribute to retinal pigment epithelium (RPE) degeneration. The aim of this study was to determine whether choroidal perfusion is reduced in RP and whether this is correlated with the stage of disease. METHODS: Ocular pulse amplitude (OPA) evaluated with the ocular blood flow (OBF) system, applanation intraocular pressure (IOP), visual fields, blood pressure (BP), and heart rate (HR) were measured in 75 RP patients having stage RP-I (stage I: visual field size: 7.85-14.67 cm(2); n = 22), stage RP-II (stage II: visual field size: 2.83-7.84 cm(2); n = 29), or stage RP-III (stage III: visual field size: 0.52-2.82 cm(2); n = 24) were compared with matched healthy controls and each other. RESULTS: Neither IOP nor systemic perfusion parameters were significantly (p >0.1) altered, but OPA (mm Hg) in RP patients beginning with stage RP-II (1.6 (0.1), 27.3%, p<0.0001), and RP-III (1.2 (0.1), 45.5%, p<0.0001) was significantly reduced when compared with matched subgroups from a pool of healthy controls (2.2 (0.1), n = 94). CONCLUSIONS: OPA can be used neither for early clinical detection of RP nor to follow the natural course of the disease. However, our data show that in advanced stages of RP not only the retina but also the choroidal circulation is affected.

Adult↗
PubMed2000

Tri-iodothyronine treatment in children after cardiac surgery: a double-blind, randomised, placebo-controlled study.

BACKGROUND: Serum thyroid hormone concentrations decline transiently during critical illness and after surgical procedures. We investigated prospectively the endocrine and haemodynamic effects of tri-iodothyronine treatment after cardiopulmonary bypass operations in children with congenital cardiac malformations. METHODS: We did a randomised, double-blind, placebo-controlled trial, in which 40 children (median age 0.6 years; range 2 days to 10.4 years) were randomly assigned placebo (saline) or one daily infusion of tri-iodothyronine (2 microg/kg bodyweight on day 1 after surgery and 1 microg/kg bodyweight on subsequent postoperative days up to 12 days after surgery. Before and 2 h, 24 h, and 72 h after the first infusion, plasma concentrations of thyroid hormones were measured by RIA, and systolic cardiac function was evaluated by echocardiography. During the postoperative course intensive-care measures were assessed by use of the therapeutic intervention scoring system. FINDINGS: In all patients, postoperative plasma concentrations of thyrotropin, thyroxine, free thyroxine, tri-iodothyronine were abnormally low and plasma concentrations of reverse tri-iodothyronine were raised. After start of treatment, tri-iodothyronine was significantly higher in patients given tri-iodothyronine than in those receiving placebo, whereas thyrotropin, thyroxine, free thyroxine, and reverse tri-iodothyronine remained similar in the two groups. At discharge, thyroid hormones of all patients were within the normal range, but thyrotropin secretion increased to plasma concentrations higher than those seen before treatment. The mean change of cardiac index was significantly higher in children given tri-iodothyronine (20.4% [SD 19.6] vs 10.0% [15.2]; p=0.004). Systolic cardiac function improved most in patients given tri-iodothyronine after longer cardiopulmonary bypass operations. Overall, patients given tri-iodothyronine had significantly lower mean treatment scores. INTERPRETATION: Treatment of children with tri-iodothyronine after cardiopulmonary bypass operations raises tri-iodothyronine plasma concentrations and improves myocardial function especially in patients with low postoperative cardiac output without adverse events, and without delaying postoperative recovery of thyroid function. Furthermore, tri-iodothyronine reduces the need for postoperative intensive care.

Cardiac Output↗
PubMed2000

Clonidine provides an allergy-free alternative in glaucoma patients with proven allergy to apraclonidine.

PURPOSE: The aim of this study was to determine allergic responses to clonidine hydrochloride 0.25% in glaucoma patients with proven allergic reaction to apraclonidine 0.5%. METHODS: Fifteen consecutive glaucoma patients with allergic reaction to apraclonidine were prospectively challenged with clonidine hydrochloride 0.25% and evaluated for recurrence of allergic reactions and efficacy of treatment. Intraocular pressure (IOP), conjunctival hyperemia, blood pressure and resting pulse rate were determined at baseline and after 1, 3, 6 and 12 months. RESULTS: None of the patients developed ocular allergic reaction during 12 months on clonidine therapy. Blood pressure and pulse rate did not change significantly with clonidine treatment. Clonidine caused a significant reduction of IOP from baseline. In one patient, topical clonidine caused fatigue, dizziness and dry mouth. CONCLUSION: Clonidine did not cause allergic reaction in patients with proven allergy to apraclonidine, indicating that there is no cross-reactivity with apraclonidine. Due to the small series, however, we cannot assume that allergy will not occur with clonidine 0.25% given time and a larger number of patients.

Adolescent↗
PubMed2000

[3D-spectrogram of the doppler signal in real time].

AIM: Doppler signals are normally displayed as an x/y-graph. The frequency is plotted in the y-direction, and the intensity is represented by the brightness. This represents less information than is contained in the acoustic signal: often one can hear more one can see. We are investigating the question as to whether it is feasible to render the complete information visible without the use of expensive additional equipment. METHOD: The sound card (SB16 P&P value edition) in a Pentium-PC (200 MHz 32 MB RAM) was used as a 16 bit dual channel a/d converter and connected to the ultrasound system Sonoline Elegra (Siemens, Erlangen, Germany). We used a standard 32 bit dual channel real-time FFT-software (SpectraPro, Sound Technology, California) to display a 3D-spectrogram on the PC-screen in real-time mode. This system was first tested on a flow model both with laminar steady flow and with pulsatile flow. Following this, measurements were made of the arteries and veins in healthy volunteers. RESULTS: In the 3D-Spectrogram the character of the flow can easily be seen. The quantitative parameters of velocity (Doppler frequency), direction and intensity of flow can be readily determined. Additional information about quality of flow, erythrocyte clusters and changes occurring in areas of slight stenoses can be used for diagnostic evaluation. The orthograde and retrograde flow are displayed separately using the dual channel technique. The arterial and venous flow in small and closely neighbouring vessels, such as the central retinal artery and vein, can easily be differentiated. The venous flow in particular is more turbulent in the 3D-spectrogram than would be expected from the normal display mode. CONCLUSION: The 3D-spectrogram provides much additional information in comparison with the normal Doppler spectrogram of the ultrasound system. This 3D-spectrogram can be easily obtained using inexpensive standard hard- and software.

Arteries↗
PubMed2000

[Doppler sonography of the short posterior ciliary artery in patients with primary open angle glaucoma].

AIM: The area of primary damage in glaucomas is the optic nerve head. This region is directly supplied by the peripapillary choroid and the short posterior ciliary arteries (SPCA). This study was designed to evaluate the choroidal and SPCA haemodynamics in high tension (HTG) and normal tension (NTG) primary open angle glaucoma patients, as well as in healthy controls (CTL). METHODS: 20 HTG, 12 NTG, and 32 age matched volunteers (CTL) without clinically relevant extracranial stenosis of the carotid arteries were evaluated for ocular pulse amplitude (OPA; OBF-System OBF Labs, UK) and for temporal SPCA peak systolic flow (PSV), enddiastolic flow (EDV), pulsatility (PI) and resistance indices (RI) using a 9 MHz phased array (Elegra Advanced System; Siemens, Germany). RESULTS: (mean +/- SD): In the control group the PSV (cm/s) of the SPCA was 10.90 +/- 1.53; EDV (cm/s) was 3.24 +/- 0.24, PI was 1.30 +/- 0.39, RI was 0.69 +/- 0.11, OPA (mm Hg) was 2.2 +/- 0.25; IOP (mmHg) was 14.6 +/- 1.5. When compared to CTL matched for age, sex, and refraction, NTG-patients showed the following results: OPA was significantly (p < 0.05) reduced, dopplersonography showed a significant (p < 0.05) reduction in diastolic flow patterns and a significant (p < 0.05) increase in PI and RI. In HTG-patients the parameters investigated where not significantly (p > 0.05) altered. CONCLUSION: These data suggest reduced haemodynamics in the choroid and in the SPCA of NTG patients, which may contribute to progression of the optic neuropathy. In HTG the Doppler parameters and the OPA are not altered compared with the control group.

Ciliary Arteries↗
PubMed2000

Ocular pulse amplitude in diabetes mellitus.

BACKGROUND: The influence of diabetes mellitus on ocular pulse amplitude (OPA), an indirect measure of choroidal perfusion, is unclear. METHODS: OPA, using the Langham ocular blood flow (OBF) system, applanation intraocular pressure (IOP), systemic blood pressure (BP), heart rate, and haemoglobin (Hb) A(1c) were measured in patients with insulin dependent diabetes mellitus (IDDM) with no (DR-0, n = 22) non-proliferative (DR-1, n = 24), and proliferative (DR-2, n = 18) diabetic retinopathy. RESULTS: Neither local (OPA, IOP) nor systemic perfusion parameters (BPs, HR) nor HbA(1c) were significantly altered in DR-0, DR-1, or DR-2 IDDM patients. CONCLUSION: Choroidal circulation remains unaffected as diabetic retinopathy advances.

Adult↗