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Biomedical subjects

J Krauss

Publications and source records attributed to J Krauss.

At least 19 recordsLinked to original sources
PubMed2006

New approach towards cytotoxic furyl macrolactones by ring closing metathesis.

Furan-2-ylalkenols 2a-d were esterified with undec-10-enoyl chloride and the resulting esters were cyclized to unsaturated 2- and 3-furyl macrolactones by ring closing metathesis using Grubbs catalyst I. Hydrolysis of the macrolactone 4b with NaOH led to the furylalkenoic acid and reaction of 4c with tert-butyllithium gave a tert-butyl ketone. Some of the resulting compounds were tested in the MTT assay for their cytotoxic activities against HL 60 cells and at the National Cancer Institute (NCI) against 60 cancer cell lines. The compounds only showed cytotoxic activities in the muM range.

Antineoplastic Agents↗
PubMed2006

Early periinsular hemispherotomy in children with Sturge-Weber syndrome and intractable epilepsy--outcome in eight patients.

BACKGROUND: Periinsular hemispherotomy is used to treat catastrophic epilepsy in hemispheric lesions. It avoids complications of tissue resection performed in other hemispherectomy procedures. We report on the effectiveness, complications, and neurological sequelae in patients with Sturge-Weber syndrome (SWS). METHODS: Eight patients (mean age at operation 15 months, mean surveillance time 7.1 years, 5 girls) were operated between 1994 and 2000, one with additional subpial resections of the insular cortex. Preoperatively hemiparesis was evident in all patients, mental retardation in six. Charts were reviewed for pre- and perioperative data. Outcome data were collected by structured telephone interview and questionnaires. RESULTS: No severe complications occurred. Five patients with unilateral angiomatosis were seizure-free without medication, rare non-disabling seizures occurred in one. Two patients with bilateral angiomatosis had seizure reduction of > 90%. Hemiparesis deteriorated in all patients with a marked deficit of hand function and less severe deficit in the lower extremity and trunk. Seven became ambulatory and achieved community language. Mental development improved with seizure control. Six patients have learning disability, two are mentally handicapped. CONCLUSION: Periinsular hemispherotomy is a valuable treatment modality in this patient group. The sequelae of hemiparesis, hemianopsia, and developmental delay must be seen in relation to the natural course in severe SWS.

Child↗
PubMed2006

[Congenital skin lesions in occult spinal dysraphism--what is typical?].

Occult spinal dysraphism (OSD) includes a group of spinal malformations covered by intact skin. Neurological sequelae include paresis and sensory deficits in the lower limbs, neurogenic bladder and bowel disturbances, pain and neuro-orthopaedic syndrome as well as a high risk for secondary neurological deterioration. In up to 80 % of the cases, OSD is accompanied by lumbosacral skin anomalies. In this article, an overview on the main forms of OSD and characteristic skin lesions is given, which can guide the clinician to early diagnosis and appropriate diagnostic work-up and, if necessary, therapeutic intervention.

Humans↗
PubMed2005

Cutaneous lesions in occult spinal dysraphism--correlation with intraspinal findings.

OBJECTS: This study was conducted to investigate the frequency and type of cutaneous stigmata in different forms of occult spinal dysraphism (OSD) and their correlation to the underlying malformation. METHODS: Fourteen different forms of spinal malformations were identified in 358 operated patients with OSD. Most frequent findings (isolated or in combinations) were spinal lipoma, split cord malformation, pathologic filum terminale, dermal sinus, meningocele manqué, myelocystocele and caudal regression. Stigmata were present in 86.3% of patients, often in various combinations. Using a binary logistic regression analysis, significant correlations with distinct malformations were found for subcutaneous lipomas, skin tags, vascular nevi, pori, hairy patches, hypertrichosis, meningoceles and "cigarette burn" marks. CONCLUSIONS: Cutaneous markers in a high percentage accompany spinal malformations. Due to the correlations of different stigmata to distinct malformations, they can aid the clinician in further diagnostic and therapeutic work.

Adolescent↗
PubMed2005

Hydrocephalus in craniosynostosis: a review.

INTRODUCTION: Ventricular dilatation in the presence of primary craniosynostosis is a unique condition with respect to pathogenesis, clinical significance, and morphological appearance. It is rarely observed in nonsyndromic craniosynostosis, and in these cases usually attributable to coincidental disorders. Conversely, it is a common feature of syndromic craniosynostosis, affecting at least 40% of patients with Crouzon's, Pfeiffer's or the Apert syndrome. Shunt-dependent hydrocephalus is predominantly associated with Crouzon or Pfeiffer syndrome while in the Apert syndrome the usual finding is nonprogressive ventriculomegaly which, however, may also occur in some cases of Crouzon syndrome. PATHOGENESIS: The pathogenesis of progressive hydrocephalus remains somewhat obscure, a hypoplastic posterior fossa and a venous outlet occlusion at the skull base being the main causative factors discussed in literature. Ventriculomegaly may reflect primary brain maldevelopment or in some cases even a compensated state of increased cerebrospinal fluid (CSF) outflow resistance. CLINICAL EVALUATION: Clinical evaluation is mainly aimed at identifying progressive hydrocephalus, but diagnosis is hampered by the fact that classical clinical signs may be absent, and that ventricular dilatation will often become evident only after decompressive cranial surgery. Moreover, mild ventriculomegaly may in some cases coexist with intracranial hypertension from craniostenosis. Therefore, careful monitoring of intracranial pressure and ventricular size in the pre- and postoperative period is a diagnostic mainstay. CONCLUSION: In true hydrocephalus ventriculo-peritoneal shunting is currently the single promising mode of treatment.

Cranial Sutures↗
PubMed2004

Impact of antibody framework residue VH-71 on the stability of a humanised anti-MUC1 scFv and derived immunoenzyme.

Anti-MUC1 single-chain Fv (scFv) fragments generated from the humanised antibody huHMFG1 had adequate antigen-binding properties but very poor stability irrespective of the applied linker or domain orientation. Mutagenesis of heavy-chain framework residue V(H)-71, previously described as a key residue for maintaining the CDR-H2 main-chain conformation and thus important for antigen binding, markedly stabilised the scFv while having only a minor effect on the binding affinity of the molecule. Because of its improved stability, the engineered fragment exhibited immunoreactivity with tumour cells even after 7 days of incubation in human serum at 37 degrees C. It also showed, in contrast to the wild-type scFv, a concentration-dependent binding to the target antigen when displayed on phage. When fusing the scFv to the recombinant ribonuclease rapLRI, only the fusion protein generated with the stable mutant scFv was able to kill MUC1(+) tumour cells with an IC(50) of 80 nM. We expect this novel immunoenzyme to become a promising tool for the treatment of MUC1(+) malignancies.

Amino Acid Sequence↗
PubMed2004

Subdural enhancement on postoperative spinal MRI after resection of posterior cranial fossa tumours.

In malignant brain tumours which may disseminate staging, usually by cranial and spinal MRI is necessary. If MRI is performed in the postoperative period pitfalls should be considered. Nonspecific subdural contrast enhancement on spinal staging MRI is rarely reported after resection of posterior fossa tumours, which may be mistaken for dissemination of malignancy. We investigated the frequency of spinal subdural enhancement after posterior cranial fossa neurosurgery in children. We reviewed 53 postoperative spinal MRI studies performed for staging of paediatric malignant brain tumours, mainly infratentorial primitive neuroectodermal tumours 2-40 days after surgery. There was contrast enhancement in the spinal subdural space in seven cases. This was not seen in any of eight patients who had been operated upon for a supratentorial tumour. After resection of 45 posterior cranial fossa tumours the frequency of subdural enhancement was 15.5%. MRI showing subdural enhancement was obtained up to 25 days postoperatively. No patient with subdural enhancement had cerebrospinal fluid (CSF) examinations positive for tumour cells or developed dissemination of disease in the CSF. Because the characteristic appearances of subdural contrast enhancement, appropriate interpretation is possible; diagnosis of neoplastic meningitis should rarely be impeded. Because of the striking similarity to that in patients with a low CSF-pressure syndrome and in view of the fact that only resection of tumours of the posterior cranial fossa, usually associated with obstructive hydrocephalus, was followed by this type of enhancement one might suggest that rapid changes in CSF pressure are implicated, rather the effects of blood introduced into the spinal canal at surgery.

Adolescent↗
PubMed2003

[Differential infratentorial brain tumor diagnosis in children].

With the exception of the first year of life, infratentorial brain tumors are more frequent in the first decade than tumors in the supratentorial compartment. In particular these are cerebellar low-grade astrocytomas, medulloblastomas, brainstem gliomas and ependymomas of the fourth ventricle. The morphology on MRI and CT and the mode of dissemination permit differential diagnosis in many cases. To allow correct stratification into different treatments in possibly disseminating malignant brain tumors, knowledge of the status of dissemination is essential, and therefore not only cranial but also spinal MRI is indispensable for staging. If the spinal MRI is performed in the immediate postoperative period, knowledge of the normal non-specific purely postoperative changes, often seen as enhancement in the subdural spinal spaces, is necessary in order to avoid misinterpretation as meningial seeding. The differential diagnosis of pediatric infratentorial brain tumors and the morphology of subdural enhancement are illustrated with typical images. The natural history of the most frequent tumors and its importance for treatment decisions is discussed in light of the literature.

Brain↗
PubMed2002

Nonlinear charge spreading visualized in voltage-controlled lateral superlattices.

Voltage-controlled lateral potential superlattices are used to dramatically increase the lifetime of photogenerated carriers in a quantum well. These long lifetimes, together with the ability to deliberately trigger radiative recombination, enable us to directly visualize the spreading character of nonlinear Maxwell relaxation of 2D charges along narrow channels. Our system allows for temporal and spatial resolution of Maxwell kinetics, usually a very fast process and difficult to observe. The observed spreading dynamics of a 2D hole plasma is in perfect agreement with our nonlinear model.

Journal Article↗
PubMed2002

Synthesis and antimicrobial activity of hydroxyalkyl- and hydroxyacyl-phenols and their benzyl ethers.

New phenolic compounds with hydrophilic side chains were prepared from 4-benzyloxybenzaldehyde and alkenyl magnesium bromides, followed by Sharpless dihydroxylation and hydrogenolytic removal of the benzyl group. The resulting compounds were tested in an agar diffusion assay against gram positive bacteria, gram negative bacteria, and against the fungi Candida glabrata and Aspergillus niger.

Anti-Bacterial Agents↗
PubMed2002

First national survey on management strategies in non ST-elevation acute ischaemic syndromes in Argentina. Results of the STRATEG-SIA study.

AIMS: To assess the management strategies applied in non-ST elevation acute ischaemic syndromes in Argentina, the factors influencing the choice of treatment, and their relationship to short- and long-term (1 year) patient outcomes. METHODS AND RESULTS: We conducted a 1 month, prospective, population-based survey in 77 hospitals (all over the country). We recruited 492 patients (age 63.9+/-11.7 years, male sex 68.3%, and 59.8% acute ischaemic ECG changes). Subjects were stratified according to the AHCPR classification as: high risk 62.2%, intermediate 25.0% and low 12.8%. At 1 year, the rate of death or myocardial infarction according to risk category and invasive procedures employed were: high risk (angioplasty 5.4% vs coronary artery bypass grafting 12.1% vs medical treatment 17.2%; P=0.001), intermediate risk (angioplasty 5.7% vs coronary artery bypass grafting 12.5% vs medical treatment 4.7%, P=ns), and low risk (angioplasty 10.0% vs coronary artery bypass grafting 15.2% vs medical treatment 1.9%; P<0.001). In the overall population, the 1 year event rate was not significantly different between the invasive and medical treatment groups (11.5% vs 7.2%, P=0.09). CONCLUSIONS: A routine, unselected invasive approach in non-ST elevation acute ischaemic syndromes in Argentina is associated with no apparent improvement of patients' outcome.

Aged↗
PubMed2001

Analysis of the TSC2 gene in human medulloblastoma.

Medulloblastoma (MB) represents the most frequent malignant brain tumor of childhood. Recent studies have shown that deregulation of developmental control genes may play an important role in its pathogenesis. Tuberous sclerosis is associated with hamartomas and cortical tubers, consisting of both glial and neuronal cellular components. MBs can also show markers of these lineages, raising the question of the potential involvement of TSC genes in these malignant tumors. Here we investigated tuberous sclerosis 2 (TSC2), one of the two genes responsible for tuberous sclerosis, in sporadic MBs. We analyzed MBs for allelic losses at the TSC2 locus and for the frequency of a polymorphism first described in gangliogliomas. Sixty-eight MBs were examined for this polymorphism located in intron 4, 3 base pairs 5' to the first coding nucleotide of exon 5. The distribution of the alleles was significantly different in MBs as compared to 208 control samples, (P=0.0017, Chi-square test). In MBs the frequency of the rare allele (A2) was 0.184 (18.4%), whereas in the control group it occurred in a frequency of 8.7%. Microsatellite analysis of the TSC2 region in 50 tumors did not identify allelic losses. TSC2 mRNA transcript was detectable via reverse transcription-PCR in all tumors as well as in normal cerebellum. Northern blot analysis of an MB cell line homozygous for the rare allele of the polymorphism and two other cell lines homozygous for the frequent allele revealed normal splicing patterns and normal expression levels of the TSC2 transcript. These findings may indicate that the presence of the rare TSC2 allele is associated with a predisposition for the development of MBs.

Blotting, Northern↗
PubMed2001

Intra-operative electromyographic monitoring of the lower cranial motor nerves (LCN IX-XII) in skull base surgery.

The functional preservation of lower (motor) cranial nerves (LCN) is endangered during skull base surgery. Intra-operative EMG monitoring of the LCN IX-XII was investigated in 78 patients undergoing 80 operations on various skull base tumors with regard to technical feasibility and clinical efficacy. Ongoing 'spontaneous muscle activity' (SMA) and 'compound muscle action potentials' (CMAP) following supramaximal bipolar stimulation were intra-operatively recorded applying needle electrodes into the soft palate (CN IX: n=76), the vocal cord (CN X: n=72), the trapezius muscle (CN XI: n=18), and the tongue (CN XII: n=71). From 24/22/8 cases with LCN IX/X/XII deficits (despite monitoring) only 5/6/4 remained unchanged (3-6 months postoperative). An irreversible plegia of the LCN IX/X/XII occurred in three (1/1/1) patients. In 7/6/1 patients postoperative (3-6 months) LCN IX/X/XII function was better than preoperatively. In all patients accessory nerve function remained unchanged. 'Pathological' SMA of the LCN IX/X/XII occurred in 12/16/8 cases, but in only 6/5/3 cases corresponded to postoperative LCN deficits. Corresponding 'pathological' SMA patterns were found in 18/17/5 out of 24/22/8 cases with postoperative LCN IX/X/XII dysfunction. Reproducible CMAP of LCN IX/X/XI/XII could be recorded in 59/56/11/32 patients. Approximate 'normal' values were calculated and compared to (very few) data so far given in the literature. Electromyographic monitoring proved to be a safe tool for the intra-operative identification and localization of the LCN contributing to their anatomical and functional preservation. The predictive value of standard neurophysiological parameters for functional outcome, however, is limited.

Adolescent↗
PubMed2001

Total synthesis of (+/-) tanikolide.

The natural polyketide (+/-)-tanikolide (1) was prepared in eight steps starting from hex-5-enol. Key steps in this synthesis are a Sharpless dihydroxylation and a Grignard reaction between an alkyl halogenide and a ketone. The lactonization occurred spontaneously during the oxidation of the primary alcohol function to the carboxy group.

Anti-Bacterial Agents↗
PubMed2001

New ultrasound techniques and their application in neurosurgical intra-operative sonography.

We describe a variety of new ultrasound techniques by their physical background, potentials and applications regarding usefulness during intra-operative neurosurgical procedures. Transducers like high-frequency and small rotating probes fitting into neuroendoscopes, imaging techniques as extended field-of-view technique, harmonic imaging, echo-enhancers, 3-D imaging and the real-time integration of neurosonography with pre-operative CT- or MR-data are mentioned. The technical or physical principles are explained, followed by a discussion of these techniques from available literature dealing with their intra-operative neurosurgical applications and the experience of the authors with the techniques. With higher frequencies micromillimeter imaging is possible and small probe allows endoneurosonography. Echo-enhancers and harmonic imaging improve the signal-to-noise ratio and 3-D imaging and extended field-of-view techniques allows a better understanding of the pathoanatomy. With the real-time integration of intra-operative ultrasound images and pre-operative CT or MR images additional information, like hemodynamic pattern, are available for the neurosurgeon. Although until now only a limited number of reports about new sonographic techniques during intra-operative application in neurosurgery exist, the methods seem to be promising in creating images easier to understand, incorporating more information about pathoanatomy and supplying the neurosurgeon with information additional to that provided by CT and MRI.

Central Nervous System↗
PubMed2001

Surgical management of tethered spinal cord in adults: report of 54 cases.

OBJECT: The clinical features specific to tethered cord syndrome (TCS) in adults as well as factors determining outcome and prognosis have rarely been addressed systematically. The authors studied 56 patients, 54 of whom were treated surgically over the last 16 years. METHODS: In 17 patients who had been asymptomatic during childhood, TCS was diagnosed 8 years after onset of symptoms. Tethered cord syndrome was diagnosed 4 years after worsening in 39 patients with neurological signs or symptoms since childhood. The patients were followed for an average of 8 years. Features specific to adult-age presentation included nondermatomal pain aggravated by movement in 34 patients and conditions such as pregnancy and childbirth (in five of 11 pregnant patients). The most frequent tethering lesions were lipoma in 32, tight terminal filum in 28, and split cord malformation and secondary adhesions in 12 patients, respectively. Improvement or stabilization of symptoms at 6 months after surgery was noted in 46 (85%) of 54 patients. Improvement in pain status was most frequent (86%) followed by improvements in spasticity (71%), bladder dysfunction (44%), and sensorimotor deficits (35%). Factors associated with adverse outcome included preoperative duration of neurological deficits more than 5 years and incomplete untethering. On average, 8 (80%) of 10 patients with incomplete untethering developed recurrent symptoms 5 years after surgery compared with only seven (16%) of 44 patients in whom complete untethering was achieved. Seven patients underwent reoperation and in five of them stabilization of symptoms was attained. At a mean follow up of 8 years, 46 (85%) of the 54 surgically treated patients were in stable neurological condition, including those in whom reoperation was performed. CONCLUSIONS: Surgery for TCS is as beneficial in adults as it is in children. Its success depends on early diagnosis and complete untethering of the spinal cord.

Adolescent↗