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Biomedical subjects

S Schaefer

Publications and source records attributed to S Schaefer.

134 records · Page 8Linked to original sources
PubMedDate not supplied

A simple method for fixation and microdissection of frozen fresh tissue sections for molecular cytogenetic analysis of cancers.

Microdissection has been widely used for procuring DNA from specific microscopic regions of formalin fixed, paraffin embedded tissue sections. We have developed a method for fixation and microdissection of frozen fresh biopsy tissue sections. Five micrometer frozen fresh tissue sections were fixed with ethanol and stored at room temperature. Well defined regions from hematoxylin and eosin (H & E) stained or unstained sections were briefly steamed and microdissected using a needle. The dissected tissue was digested with proteinase K and DNA was isolated. Whole genome amplifications were obtained by degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR) from these samples. The reliability of this technique was demonstrated by comparing conventional comparative genomic hybridization (CGH) with DOP-PCR-CGH. The advantages of this method are that frozen fresh sections can be fixed easily and stored for more than 4 years, it is easy to microdissect and pick-up very minute regions (0.1 mm(2)), and it is rapid; microdissection and purification can be accomplished within 3 h. Using DNA from microdissected sections, DOP-PCR-CGH revealed genetic abnormalities more accurately than conventional CGH. Although this novel method was demonstrated using DOP-PCR-CGH, we believe that it will be useful for other genetic analyses of specific small regions and cell populations. We also observed whether storage time, H & E staining and crude DNA extracts affected the quality of amplified DNA. DNA integrity was maintained for at least 49 months in ethanol fixed sections that were stored at room temperature, but DNA was gradually degraded after one month if the ethanol fixed sections had been H & E stained and stored. When crude DNA extracts from H & E stained sections were used, the size of the DOP-PCR product was reduced. Our study suggests that ethanol fixed tissue sections may be stored at room temperature for at least 4 years without DNA degradation, the H & E stains may not affect the quality of amplified DNA, but H & E or other components in the staining process may reduce the size of DOP-PCR product, which is critical for the quality of CGH hybridization.

Biopsy↗
PubMedDate not supplied

Risk stratification prior to vascular surgery: does the location of a dipyridamole thallium scintigram defect provide prognostic information?

BACKGROUND: While the value of myocardial scintigraphy using dipyridamole thallium is accepted for risk assessment prior to vascular surgery, it is unknown whether the location of the thallium abnormalities provides prognostic information. METHODS: Records from 435 consecutive patients scheduled for vascular surgery were reviewed and patients with dipyridamole thallium abnormalities involving the anterior distribution (ANTERIOR n = 62), or inferior or inferolateral distribution (INFERIOR n = 105) were assessed for cardiac complications of surgery (death, myocardial infarction, unstable angina or ischemic congestive heart failure). RESULTS: Patients with a normal dipyridamole thallium scintigraphy had few surgical cardiac complications: 2/86 (2%). Patients with an ANTERIOR dipyridamole thallium defect had a 12% incidence of surgical cardiac complications (7/57) without any cardiac deaths, while patients with an INFERIOR dipyridamole thallium defect had a similar incidence of surgical cardiac complications, 18% (18/100; p = 0.65 vs. ANTERIOR) including 4 cardiac deaths. CONCLUSIONS: Significant inferior or inferolateral dipyridamole thallium scintigraphy abnormalities are not associated with a lower risk of cardiac complications following vascular surgery than anterior abnormalities. Rather, any clearly abnormal dipyridamole thallium study is a marker for increased risk of perioperative events and may warrant further evaluation and treatment.

Aged↗
PubMedDate not supplied

Ct air-contrast scanning of the internal auditory canal.

Two hundred and four patients with audiometric and vestibular findings suggestive of a retrocochlear lesion were studied prospectively by computed tomographic scan with air contrast of the internal auditory canal. With this technique tumor limits are clearly defined. In the absence of disease the internal auditory canal has been completely air-filled in over 97% of cases. Soft tissue masses occluding the internal auditory canal were demonstrated in 11 patients. Four studies were inconclusive and there was one false positive. Headaches have been the only side effect and there have been no complications. In reporting their results the authors examined the indications, accuracy and limitations of this technique. This study demonstrates that computed tomographic scan with air contrast of the internal auditory canal should be considered as the radiologic procedure of choice for the evaluation of small acoustic tumors.

Cerebellar Neoplasms↗
PubMedDate not supplied

Magnetic resonance imaging findings and correlations in spasmodic dysphonia patients.

A sample of 19 spasmodic dysphonia (SD) patients was selected from a larger population of such patients to undergo magnetic resonance imaging (MRI), auditory brain stem response (ABR) testing, speech analysis, and extensive physical examination. Six patients had abnormal spin-echo MRI findings, ranging from infarcts within the basal ganglia to demyelinating lesions within the supralateral angles of the lateral ventricles. A weakly positive correlation was noted between the abnormal MRI findings and an abnormal ABR. The lack of a significant correlation between the MRI findings and other predictors of brain stem and midbrain disease, and the current spatial resolution limitations of MRI, suggest that we are visualizing the associated lesions rather than the actual foci of SD. The range of MRI findings is consistent with the concept that SD is a voice disorder in a heterogeneous patient population.

Adult↗
PubMedDate not supplied

Accuracy of implanted port placement with the use of the electromagnetic CathTrack catheter locator system.

PURPOSE: To test whether an electromagnetic guidance system such as CathTrack would allow long-term central venous access devices to be reliably placed at a decreased cost and without radiation exposure to patients and staff. The following study was undertaken to verify accuracy of the CathTrack system for catheter placement and to develop guidelines for its use. METHODS: Twenty-nine consecutive patients were prospectively enrolled in the study and taken to the operating room for implantation of a permanent central venous access port. By protocol, the CathTrack system was used to guide initial catheter positioning using the center of the third intercostal space along the right sternal border as the desired external target. Fluoroscopy was then used to visualize tip position and relocate the catheter tip to the exact position desired by the surgeon. RESULTS: Catheter placement using the CathTrack system was successfully accomplished in 27 out of 29 patients. In two instances CathTrack was abandoned and fluoroscopy utilized because of difficulty in threading the initial guidewire into the superior vena cava. CONCLUSION: The CathTrack electromagnetic locator system can be used to reliably position catheters for the establishment of long-term central venous access. Decreased cost and elimination of radiation exposure are distinct advantages of this system over fluoroscopy.

Journal Article↗
PubMedDate not supplied

Carotid artery resection and replacement in patients with head and neck malignant tumors.

Tumor involvement of the carotid artery with head and neck cancers may be present either simultaneously with the primary lesion or more often appears at a later date following resection of the primary tumor. Management of the secondary tumor consists of its resection together with the involved carotid artery with or without carotid artery reconstruction. The Authors are convinced that the best chance for cure of patients with advanced head and neck squamous cell cancers involving the carotid artery is radical extirpation with ablative surgery in the form of en block resection of the primary lesion, the secondary tumor, and the involved carotid artery followed by immediate revascularization. This bold approach was carried out in two male patients, 48 and 61 years of age, followed by chemotherapy and radiation therapy in one and radiation therapy alone in the other, with excellent results. Dermal grafts were placed over the entire length of the arterialized veins to protect them from radiation injury. Based on this limited experience and excellent results, we recommend this one-stage surgical ablative procedure in well selected patients. However, cooperation between the ENT and vascular surgeons, strict adherence to the principles and techniques of vascular surgery, and coverage of the arterialized vein with a dermal graft is absolutely essential.

Anastomosis, Surgical↗