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Biomedical subjects

G Fricke

Publications and source records attributed to G Fricke.

At least 19 recordsLinked to original sources
PubMed1999

Abnormal subcortical somatosensory evoked potentials indicate high cervical myelopathy in achondroplasia.

UNLABELLED: Children with achondroplasia may have high cervical myelopathy due to stenosis of the cranio-cervical junction resulting in neurological disability and an increased rate of sudden death. To detect myelopathy we recorded somatosensory evoked potentials (SEPs) after median nerve stimulation in 30 patients with achondroplasia aged 13 months to 18 years (mean 6 years). In addition to the conventional technique of recording the cortical N20 and the central conduction time (CCT), we employed a noncephalic reference electrode recording the subcortical waveforms N13b and P13. generated near the cranio-cervical junction. The findings were related to the clinical status and MRI results. Eighteen patients had MRI evidence of spinal cord compression with indentation or narrowing of the upper cervical cord, and 13 showed signs of myelomalacia. Seven patients had neurological abnormalities. The sensitivities of the SEPs were 0.89 for cervical cord compression, 0.92 for myelomalacia and 1.0 for the clinically symptomatic patients. There were no false-positive results. The subcortical SEPs were more sensitive than the conventional recordings. However, the conventional SEPs were highly specific in the most severely affected patients; here the specificity was 1.0 for patients with myelomalacia and 0.96 for symptomatic patients. Postoperative SEPs improved after occipital decompression in two children. CONCLUSION: The analysis of somatosensory evoked potentials, in particular of subcortical tracings, is useful in the detection of early cervical myelopathy in children with achondroplasia. Early neurosurgical decompression may prevent irreversible damage.

Achondroplasia↗
PubMed1995

Absence of mutations in the WT1 gene in patients with XY gonadal dysgenesis.

The WT1 gene is normally expressed during gonadal development and specific mutations in heterozygous form cause Drash syndrome, characterized by male pseudohermaphroditism and gonadal dysgenesis, renal failure and a predisposition for Wilms' tumour. These observations prompted us to test whether WT1 mutations are involved in isolated gonadal dysgenesis, being the most severe form of disturbance in gonadal differentiation. We studied 27 cases of 46,XY females with gonadal dysgenesis who had previously been screened for and found not to carry SRY gene mutations. We performed mutational screening of the WT1 gene with denaturing gradient gel electrophoresis. In one of these patients, a heterozygous point mutation in exon 8 was found. This mutation has previously been described in Drash syndrome and re-evaluation of the clinical data confirmed this diagnosis. Based on these results, we conclude that isolated gonadal dysgenesis is not caused by mutations in the WT1 gene.

DNA↗
PubMed1989

Distribution of serotypes and biotypes of thermophilic campylobacters in the Federal Republic of Germany: a comparison with other countries.

Thermophilic Campylobacter isolates from infected humans from the southwest of the FRG were bio- and serotyped according to Lior's scheme. Serotyping was performed with a commercially available test kit (Sopar, Brussels). C. jejuni represented about 87% of the isolates with Biotype I representing about 50% of the isolates. C. coli was found in 12% of the isolates and C. laridis in less than 1%. The most frequently identified serotypes were LIO 8, LIO 7 and LIO 4. The results are compared with investigations from seven other countries and with one investigation from northern Germany.

Bacteriological Techniques↗
PubMed1989

The pharmacokinetics of ticarcillin/clavulanate acid in neonates.

The pharmacokinetics of a 25:1 combination of ticarcillin and clavulanate were studied in nine pre-term and seven full-term neonates. Pre-term neonates with a gestational age ranging from 30 to 36 weeks received 83.3 mg of ticarcillin and 3.3 mg of clavulanate per kg bw and full-term neonates with a gestational age from 39 to 43 weeks received 100 mg of ticarcillin and 4 mg of clavulanate per kg bw 8-hourly, each by a slow infusion over 10 min. Serum was sampled 15, 30, 60, 120, 240 and 480 min after the first dose and trough samples were additionally obtained on the fourth day of treatment. The patients were allocated to Groups 1-3 on the basis of the pharmacokinetic characteristics obtained. Group 1 comprised seven full-term babies. Group 2 contained seven pre-term neonates with a birth weight between 1915 and 2650 g and Group 3 consisted of two pre-term neonates of low birth weight (1400 g and 1640 g). Mean (+/- S.E.) pharmacokinetic characteristics of Group 1 patients for ticarcillin were: Cmax = 404.9 mg/l (36.0); T = 2.68 h (0.23); AUC = 1287 h.mg/l (69); Vd = 266 ml/kg (28) and for clavulanate: Cmax = 15.0 mg/l (1.2); T = 1.39 h (0.12); AUC = 30.1 h.mg/l (1.7); Vd = 263 ml/kg (22). Corresponding parameters for Group 2 patients for ticarcillin were: Cmax 278.7 mg/l (30.4); T = 4.20 h (0.49); AUC = 1107 h.mg/l (57); Vd = 338 ml/kg (35) and for clavulanate: Cmax = 8.4 mg/l (0.56); T = 2.56 h (0.18); AUC = 27.1 h.mg/l (2.0); Vd = 414 ml/kg (29). Drug accumulation was not observed in patients of Groups 1 and 2. Each of the two patients of Group 3 presented a pharmacokinetic profile which was considerably different from those observed in Groups 1 and 2. While in patients of the latter group the peak serum concentrations were achieved at 15-30 min after the end of infusion, these concentrations occurred between 120 and 240 min in one of the Group 3 patients. In the other Group 3 patient a remarkable drug accumulation was noted but was not associated with clinical or laboratory evidence of toxicity. These data show that ticarcillin and clavulanic acid in these dose ranges achieved adequate peak and trough concentrations in pre-term and full-term neonates.

Clavulanic Acids↗
PubMed1987

Rapid and improved gas-liquid chromatography technique for detection of hippurate hydrolysis by Campylobacter jejuni and Campylobacter coli.

A gas-liquid chromatographic method which requires no chloroform extraction of the split products has been investigated for the detection of hippurate hydrolysis by Campylobacter spp. This technique gave better reproducibility than other tests also used in this study and allows the routine use of the gas-liquid chromatographic method for identification of Campylobacter isolates.

Benzoates↗
PubMed1986

[Pulsed Doppler echocardiography in prosthetic aortic and mitral valve replacement].

In 94 subjects with normally functioning heart valve prostheses (51 aortic and 43 mitral valve prostheses) and in 35 patients with intact aortic and mitral valves, blood flow velocity within the heart and the aortic root have been recorded using pulsed Doppler velocity studies in patients with diseased valves of the left heart. In addition, a further 7 patients were investigated using invasive catheter tip velocitometry, pre- and postoperatively. The preversus postoperative changes of maximum velocity and acceleration is characterized as follows: postoperative flow velocity tracings show approximately normal profiles comparable to normal valve function. Turbulence formation is diminished and the steep uptroke of the normal flow pattern is restituted. Differences in transprosthetic blood flow patterns dependent on the implanted prosthesis model can be defined. Bioprostheses, in particular the Carpentier-Edwards device, reliably approximate normal amplitude-time characteristics. This is also true for the St. Jude Medical prosthesis with central flow properties. Velocitometric signs of valve dysfunction were detected in 9 patients: sensitivity was 100%; specificity ranged from 76% in aortic to 96% in mitral prostheses. Pulsed Doppler echocardiography therefore is a useful complement in the non-invasive haemodynamic tools and can be repeatedly applied to a patient with prosthetic cardiac valve replacement.

Aortic Valve↗
PubMed1985

[Reduction of regurgitation in aortic and mitral insufficiency by captopril in acute and long-term trials].

Afterload reduction is an accepted therapeutic principle in the management of acute aortic (Ai) and mitral insufficiency (Mi). The question whether acute and chronic converting-enzyme inhibition by captopril has a beneficial hemodynamic effect in chronic Ai and Mi has been investigated in 17 patients with Ai and 10 with Mi. Ejection and regurgitation fraction (RF) were measured by radionuclide ventriculography (RNV) before, after 25 mg captopril and after 3-5 months of long-term treatment. The humoral response of the renin-angiotensin system (RAS) was quantified by analysis of angiotensin I and II. Captopril lowered under acute and chronic treatment RF in Ai and Mi by 32%. Angiotensin II levels decreased by the same order of magnitude. Acute and chronic vasodilation was followed by a distinct but well tolerated fall in blood pressure, especially in patients with Mi. These favourable hemodynamic effects of captopril make this therapy an adjunct but not an alternative to valve replacement.

Aortic Valve Insufficiency↗
PubMed1983

[Digital subtraction angiocardiography].

One hundred patients with a variety of cardiac abnormalities were examined by digital subtraction angio-cardiography; the quality of the image was almost as good as conventional cinecardiograms. Image frequency of 25 pictures per second provides a reliable analysis of cardiac contraction and, in many situations, makes it unnecessary to perform selective angio-cardiography. Compared with selective catheter techniques, digital subtraction cardiography has various advantages. Because of its low risk and small patient stress, it is particularly suitable for follow-up examination after various therapeutic measures.

Adult↗
PubMed1983

[Clinical aspect and noninvasive diagnosis of cardiac myxomas].

The alteration of cardiac function in the presence of intracardiac tumors varies considerably according to their localization, size, and mode of insertion. Various cardiovascular diseases can be mimicked, e.g., primary valve dysfunction, cardiomyopathy, intracardiac shunts. Embolic events are frequent secondary symptoms. However, subtle noninvasive techniques such as M-mode and sector echocardiography, pulsed Doppler echocardiography, digital video subtraction angiography (DVSA), and computed tomography permit a thorough diagnosis of intracardiac tumorous masses without heart catheterization and catheter angiography. In this paper, myxomas within the left atrium (LA) and the right ventricle (RV) are described. Leading symptoms were systemic embolism and mitral stenosis (LA localization), low cardiac output and right to left shunt (RV localization). First suspicion of intracardiac tumor was raised by M-mode and sector echocardiography, whereas the diagnosis of LA myxoma was in one case missed by computed tomography and the RV myxoma was missed by right ventricular catheterization. In that case, only the four-chamber subxiphoidal sector echogram substantiated the diagnosis and explained the hemodynamic constellation of very low pulmonary pressures combined with right to left shunt. By the new technique of DVSA, all three tumors were plainly visualized. Nevertheless, echocardiography proved to be the most reliable technique of detecting intracardiac tumors.

Aged↗
PubMed1982

[Pulsed Doppler-echocardiographic study of mitral valve dysfunction].

67 patients (pts)--20 with intact cardiac valve function, 15 with pure mitral stenosis, 20 with both mitral valve insufficiency and stenosis, 12 pts with pure mitral incompetence - have been investigated by non-invasive pulsed Doppler-echocardiography (PDE) previous to invasive right and left heart catheterization. The following criteria for evaluation of the PDE registrations are adopted: 1) Time-related correlation of ECG and flow velocity. 2) Formal analysis of the flow-velocity tracings. 3) Turbulence formation. 4) Maximum duration of flow. In pure mitral insufficiency, systolic turbulence formation is detected within the left atrium, which is present according to the severity only locally or throughout the entire left atrium. We calculated a specificity for the diagnosis of mitral incompetence of 94% and a sensitivity of 78%. In mitral stenosis a severity-dependent ventricular inflow velocity is prevalent - with an insidious onset until a dome-like or saw-tooth-like profile. Grading for severity of mitral stenosis can be performed as follows: the time from onset to maximum flow velocity of the diastolic inflows is measured and related to the time period of the cardiac cycle. A specificity of PDE for mitral stenosis of 88% and a sensitivity of 91% have been found. PDE is also being applied for assessment of hemodynamic efficacy of prosthetic mitral-valve replacement. In the evaluation of mitral valve dysfunction, PDE as a non-invasive technique is of high specificity and sensitivity as compared with the hemodynamic results of invasive procedures.

Blood Flow Velocity↗