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Biomedical subjects

L Schubert

Publications and source records attributed to L Schubert.

At least 19 recordsLinked to original sources
PubMed2006

Laparoscopic ultrasound-guided resection of gastric submucosal tumors.

BACKGROUND: The laparoscopic resection of gastric stromal tumors is being performed with increased frequency. Wedge resection of anterior wall lesions is generally performed. The treatment of posterior wall lesions is still controversial. METHODS: We report three cases of gastric submucosal tumors treated by a laparoscopic wedge resection of the stomach. All lesions were localized anterior gastric wall by intraoperative ultrasound on the. In the first patient the resection was performed with an endoscopic stapler; in the other patients, ultrasonic coagulation in association with an intracorporeal suture has been used. RESULTS: All patients were successfully treated laparoscopically; there were no conversions to open surgery. In all cases the operative course was uneventful. The postoperative hospital stay ranged from 6 to 8 days. CONCLUSIONS: The results suggest that laparoscopic surgery is an adequate strategy for gastric submucosal neoplasms including gastrointestinal stromal tumors (GIST). Intraoperative ultrasound is very useful in the selection of the technical approach with or without the endoscopic stapler.

Adult↗
PubMed2003

Mutations at the SALL4 locus on chromosome 20 result in a range of clinically overlapping phenotypes, including Okihiro syndrome, Holt-Oram syndrome, acro-renal-ocular syndrome, and patients previously reported to represent thalidomide embryopathy.

We have recently shown that Okihiro syndrome results from mutation in the putative zinc finger transcription factor gene SALL4 on chromosome 20q13.13-13.2. There is considerable overlap of clinical features of Okihiro syndrome with other conditions, most notably Holt-Oram syndrome, a condition in part resulting from mutation of the TBX5 locus, as well as acro-renal-ocular syndrome. We analysed further families/patients with the clinical diagnosis of Holt-Oram syndrome and acro-renal-ocular syndrome for SALL4 mutations. We identified a novel SALL4 mutation in one family where the father was originally thought to have thalidomide embryopathy and had a daughter with a similar phenotype. We also found two novel mutations in two German families originally diagnosed as Holt-Oram syndrome and a further mutation in one out of two families carrying the diagnosis acro-renal-ocular syndrome. Our results show that some cases of "thalidomide embryopathy" might be the result of SALL4 mutations, resulting in an increased risk for similarly affected offspring. Furthermore we confirm the overlap of acro-renal-ocular syndrome with Okihiro syndrome at the molecular level and expand the phenotype of SALL4 mutations.

Abnormalities, Multiple↗
PubMed2002

[Positron emission-computed tomography in diagnosis and staging of lung neoplasms. Personal experience].

BACKGROUND: Positron emission-computed tomography (PET) scans are obtained from the accumulation of a radiotracer in tissues with altered metabolism, such as malignant neoplasms. The authors present their experience with PET, performed in 50 selected patients with lung neoplasms in the 1998-2000 period. METHODS: The indications to PET corresponded to those most frequently reported in the literature, that is: diagnosis in solitary pulmonary nodule 8 patients; mediastinal lymph node staging, 16 patients; re-evaluation after neo-adjuvant therapy, 21 patients; increased markers blood levels in the follow-up of resected patients, 5 cases. Each indication is individually discussed and compared with the data of the literature, especially regarding the role of PET and its relationship with other noninvasive and invasive diagnostic tools. RESULTS: In 47 patients (94%) diagnostic yield was reached. A false positive (acute inflammatory lesion in solitary pulmonary nodule), a false negative (no demonstration of lymphangitic intrathoracic recurrence) and a non-diagnostic result (then pathologically proved non-neoplastic) were recorded. CONCLUSIONS: Thus the authors consider PET extremely useful in the diagnosis and staging of lung neoplasms; the high cost of PET may be compensated for the reduced need for invasive diagnostic tools and, avoiding inappropriate surgical options, with favourable cost-effectiveness.Thus, PET may be indicated in most, if not in all, patients with lung neoplasms.

Adult↗
PubMed2001

Release kinetics of acyclovir from a suspension of acyclovir incorporated in a cubic phase delivery system.

Acyclovir is a widely used agent in the treatment of herpes virus infections of the skin, but owing to its poor physicochemical properties in terms of bioavailability and suboptimal formulations, the treatment is far from optimal. The liquid crystalline cubic phase system has been reported to act as a bioadhesive drug delivery system. In the present study, acyclovir was suspended in a cubic phase of glycerol monooleate (GMO) and water 65%:35% w/w, and the phase behavior and release kinetics were examined. X-ray diffraction and differential scanning calorimetry (DSC) measurements demonstrated that the cubic phase containing 1%-10% (w/w) acyclovir retains its phase condition in the temperature range investigated (20 degrees C-70 degrees C). Acyclovir can be incorporated in high amounts (approximately 40% w/w) without causing phase transition, as is shown in polarized light. This is probably because of its low solubility (approximately 0.11% w/w) in the cubic phase. The release characteristics of acyclovir incorporated as a suspension (1%-5% w/w) into a cubic phase were investigated using Franz diffusion cells. Acyclovir was quantified by high-performance liquid chromatography (HPLC). The drug was readily released from the system, and the release increased with the initial drug load concentration. About 25%-50% was released after 24 h. The release is dependent on the square root of time, and the kinetics can be described by the Higuchi theory. The rate-limiting step in the release process is most likely diffusion. The suggested theory is further supported by identical release data obtained for micronized and nonmicronized acyclovir. The fluxes for 1% and 5% w/w were 380 and 900 microg/h(1/2), respectively. Comparison of the release rates of acyclovir delivered from a cubic phase and from the commercial product, Zovir cream, showed the rate to be six times faster from the cubic phase. The results indicate that the cubic phase is a promising drug delivery system for acyclovir.

Acyclovir↗
PubMed1998

Bioadhesive drug delivery systems. I. Characterisation of mucoadhesive properties of systems based on glyceryl mono-oleate and glyceryl monolinoleate.

A group of fatty acid esters capable of forming liquid crystals has been identified as a new class of potential bioadhesive substances. The liquid crystals may act as a controlled release system. The experimental work was focused on the monoglycerides, glyceryl mono-oleate (GMO) and glyceryl monolinoleate (GML). The mucoadhesive properties of GMO and GML were demonstrated in vitro by a 'flushing' bioadhesion test system and a tensiometric method. The flushing system was validated with GMO. Mucoadhesion is influenced by the drug and excipient added, their concentrations, and the ability to form especially the cubic phase. It has been shown that the cubic phase is mucoadhesive when formed on wet mucosa, such as rabbit jejunum, and that drug added to the precursor formulation is incorporated in the cubic phase formed. Tensiometric measurements have shown that the unswollen monoglycerides have the greatest mucoadhesion, followed by the partly swollen lamellar phase and the fully swollen cubic phase. The values found for the work of adhesion were in the range 0.007-0.048 mJcm-2. The mechanism of mucoadhesion is unspecific and probably involves dehydration of the mucosa. The cubic phase of GMO and GML may be an interesting candidate for a bioadhesive drug delivery system.

Adhesiveness↗
PubMed1996

Coexpression of the interleukin-13 and interleukin-4 genes correlates with their physical linkage in the cytokine gene cluster on human chromosome 5q23-31.

Interleukin-13 (IL-13) and IL-4 are cytokines produced by T cells that are encoded by the q23-31 region of human chromosome 5. To investigate the regulation of IL-13 gene expression by T cells, we isolated and sequenced the human IL-13 gene, analyzed its 5'-flanking region for potential transcriptional activation elements, and examined its expression in nontransformed T-lineage cell populations. The human IL-13 gene was located 12.5-kb upstream of the IL-4 gene and 2-kb downstream of a CpG island. The IL-13 gene 5' flank region included a segment with sequence homology to P elements of the IL-4 promoter involved in transcriptional activation in T cells. Mutation of the IL-13 P element site significantly reduced IL-13 promoter activity in response to T-cell activation. Oligonucleotides containing the IL-13 or IL-4 P element sites specifically bound the transcriptional activator protein, nuclear factor-activated T cells, preformed (NF-ATp), when incubated with nuclear protein extracts from activated T cells. Similar to IL-4, IL-13 mRNA expression was highest in T-cell populations enriched for cells that had previously been primed in vivo or in vitro, indicating that priming increases the expression of the IL-13 and IL-4 genes in a coordinate manner. Because the primed T cells contain higher levels of nuclear NF-ATp, capable of binding to P elements of the IL-4 and IL-13 promoters, than do freshly-isolated T cells, the NF-AT-binding P elements are attractive candidates to mediate the coordinate expression of these two cytokine genes.

Adult↗
PubMed1996

Intraoperative ultrasonography (IOUS) during laparoscopic cholecystectomy.

BACKGROUND: The purpose of this study was to evaluate the usefulness of intraoperative ultrasonography (IOUS), a new method of imaging the biliary tree and related structures, during laparoscopic cholecystectomy. METHOD: An IOUS probe (Aloka, Tokyo, Japan) with a 7.5-MHz linear-array transducer was used during cholecystectomy in 124 patients with symptomatic cholelithiasis (45 men, 79 women; mean age, 48 +/- 14 years). RESULTS: The examination of the common bile duct (CBD) was excellent in 117 patients but unsatisfactory in 7 cases (5.6%) at the level of the head of the pancreas. In 5 patients, IOUS showed unsuspected choledocholithiasis: a subsequent intraoperational cholangiogram confirmed this. In five cases IOUS was able to help the surgeon to localize a Calot area obscured by inflammation. Postoperatively, one patient had an injury of the cystic duct stump: a nasobiliary tube resolved the bile leakage after 7 days. Another patient was submitted to postoperative endoscopic retrograde cholangiopancreatography (ERCP) for a choledocholithiasis recognized by a trans-cystic-tube cholangiography: the stone was suspected but not demonstrated either by laparoscopic IOUS or by intraoperative cholangiography. During the follow-up period, one patient had an episode of acute pancreatitis. ERCP showed a small stone wedged in the sphincter of Oddi. CONCLUSIONS: IOUS may be a real alternative to cholangiography during laparoscopic cholecystectomy since it is safer and offers a complete examination of the biliary tree. It has some disadvantages which can solved by additional experience.

Adult↗
PubMed1996

Technical difficulties and complications during laparoscopic cholecystectomy: predictive use of preoperative ultrasonography.

The aim of this study was to evaluate ultrasound findings as predictors of potential operative difficulties and complications during laparoscopic cholecystectomy (LC). From October 1993 to June 1995 a total of 143 patients with symptomatic cholelithiasis (50 males, 93 females, mean age 49.5 +/- 15 years) were evaluated by ultrasound (US) the day before LC. The US examination assessed six parameters: gallbladder (GB) volume, GB wall thickness, GB neck position, GB stone mobility, stone maximum size, and GB adhesions. On the basis of these US findings, a predictive judgment of technical difficulties was expressed by degree: easy, difficult, and very difficult. Altogether 101 patients presented with uncomplicated symptomatic cholelithiasis, and 42 had acute cholecystitis. The operation was predicted to be easy in 38% of cases, difficult in 49%, and very difficult in 13% with a good correlation with the surgeon's intraoperative judgment (r = 0.66). A significant association was found between stone mobility (r = 0.37), presence of adhesions (r = 0.36), and the difficulty of the procedure. The predictive US evaluation was significantly correlated with some intraoperative technical steps [dissection of Calot's triangle (r = 0.41), dissection of the gallbladder bed (r = 0.41)], and intraoperative bleeding (r = 0.27). Our results suggest that preoperative US is a useful screening test for patients undergoing LC, and it can help predict technical difficulties. On the other hand, a relevant number of cases still exist wherein the concordance between the preoperative US classification and the surgical findings is unsatisfactory. In this group the surgeon cannot safely rely on the US examination alone.

Adolescent↗
PubMed1980

Qualitative changes in DNA indicating differential DNA replication during early embryogenesis of the newt Triturus vulgaris.

During gastrulation of the newt Triturus vulgaris considerable changes in the melting behaviour and in the CsCl density gradient pattern of DNA occur. The melting curves of DNAs from mid to late gastrulae (stages 11b-12c) deviate from the regular shape. Whereas the Tm values are identical in the stages 11a (early gastrula) and 15 (early neurula), and correspond to the standard DNA (stage 36 = tailbud), a significant rise of Tm (0.8-1.2 degrees C) has been recorded in the stages 12a/b (yolk plug). The differences in melting behaviour become visible by the deviation of the curves above Tm. These deviations from the normal sigmoidal shape are caused by the fact that a portion of DNA melts at higher temperatures than usual. Therefore the thermal denaturation of DNA is completed at approximately 3-4 degrees C later than in standard DNA. Both the derivative curves and the plots on normal probability paper demonstrate a heterogeneity of DNA in the stages 11b-12c which indicates the presence of an additional GC-rich satellite fraction. These findings are confirmed by CsCl density gradient studies. Thus, in the stages 12a/b a slight shoulder on the heavy side of the gradients occurs, being absent in the other stages. From these facts we have to conclude that there is a stage-dependent multiplication and elimination of GC-rich sequences.

Animals↗
PubMed1977

Changes in the thermal denaturation profiles of DNA from different developmental stages of the newt Triturus vulgaris.

The melting profiles of DNA samples from the early gastrula and early neurula of Triturus vulgaris are essentially the same, whereas DNA from mid to late gastrula possesses higher Tm values and shows a deviation from the regular sigmoidal shape at temperatures above Tm. The plot on normal probability paper indicates a second DNA fraction which melts at higher temperatures and, consequently, it has a higher GC-content than the bulk of DNA. These facts confirm our idea that differential DNA replication occurs during gastrulation.

Animals↗
PubMed1977

[Our experience in the treatment of inguinal hernia using a silastic-dacron prosthesis].

The Authors report their experience on 50 patients suffering from inguinal hernia and treated with a plastic surgery operation preceded by subfascial introduction of a Silastic-Dacron prothesis. They describe the reported complications and relate on the frequency of relapses within a period of 3 years, comparing them with the data reported by the existing literature on this subject.

Aged↗