Frontoethmoidal encephaloceles, a study of their pathogenesis

A prospective clinical study of 30 patients with frontoethmoidal encephaloceles was performed in order to find support for a proposed theory concerning its pathogenesis, based on a previously performed embryological study and relevant findings in the literature. According to this proposed theory the pathogenesis of frontoethmoidal encephaloceles is primarily based on a disturbance in separation of neural and surface ectoderm at the site of final closure of the rostral neuropore during the final phase of neurulation in the 4th week of gestation. An insufficient occurrence of apoptosis might cause this disturbance in separation. The nonseparation of neural and surface ectoderm will result secondarily in a midline mesodermal defect. This mesodermal defect is reflected in the median skull defect at the site of the foramen caecum. The outgrowth of the nasal septum with the concomitant forward displacement of epidermis (surface ectoderm) and attached brain tissue (neural ectoderm) may act as herniating force. The patient study consisted of a clinical investigation, radiological investigations (X skull and CT scans), and surgical treatment in order to obtain specimens which were examined histologically. Clinical findings supportive of the proposed hypothesis are (1) the consistency in the location of the internal skull defect, (2) the close relationship between epidermal structures and glial tissue in 15 out of 29 specimens, and (3) the presence of a normally developed nose in combination with interorbital hypertelorism in all patients. A discussion of these findings is presented with special reference to the embryological aspects.     

Resection of residual retroperitoneal masses in testicular cancer: evaluation and improvement of selection criteria. The ReHiT study group. Re-analysis of histology in testicular cancer

Residual retroperitoneal masses may remain after chemotherapy for metastatic non-seminomatous testicular cancer, which harbour residual tumour or totally benign tissue (necrosis/fibrosis). These residual masses may be effectively removed by a surgical resection. We evaluated current selection criteria and tried to develop alternative criteria in a data set of 544 patients, who had retroperitoneal lymph node dissection of residual masses. Six resection policies were identified from the literature. Two alternative policies were developed with logistic regression analysis. Evaluation of the policies focused on the true-positive rate (resection in case of tumour), and the false-positive rate (resection in case of necrosis). It appeared that most current policies use the size of the residual mass (> or = 10 mm or > or = 20 mm) as the predominant selection criterion. This resulted in high true-positive rates (most > 90%), but false-positive rates between 37% and 87%. The alternative policies included five well-known predictors of necrosis in addition to residual mass size (primary tumour histology, prechemotherapy levels of the three tumour markers alphafetoprotein (AFP), human chorionic gonadotropin (HCG) and lactate dehydrogenase (LDH) and mass shrinkage during chemotherapy). This strategy resulted in improved true- and false-positive rates, even when categories of the predictors were simplified for practical application. We conclude that a simple statistical model, based on a limited number of patient characteristics, provides better guidelines for patient selection than those currently used in clinical practice.     

Conservative functional therapy of closed rupture of the Achilles tendon. Treatment approach and analysis of results

In a prospective study in the period from May 1989 to April 1994, 161 patients at the Unfallchirurgische Klinik in Braunschweig were treated for rupture of the Achilles tendon using a conservative functional method. A follow-up examination was carried out on 132 patients (81%) after an average of 12.6 months. Conservative therapy was indicated if dynamic ultrasonography showed sufficient adaptation of the rupture. Continuous retention of the adapted tendon fragments was guaranteed by means of special footwear that raises the back of the foot (Variostabil). The average age of the patients was 39.5 years. In 97 cases (73.5%) the injury was caused by sports. In 68 ruptures the dehiscence was compensated in plantar flexion. In 48 cases the dehiscence was 1-5 mm, and in 16 cases it was between 6 and 10 mm. The average period of hospitalization was 4.8 days (1/19). The period of inability to work was an average of 4 weeks (27.4 days (0/98)). The rupture healed on an average of 9.5 weeks (5.9/23). Complications included seven cases of re-rupture (5.3%), and, in the course of treatment, four patients (3%) suffered profound leg vein thrombosis that in one case developed into postthrombotic syndrome. In two cases there was tendovaginitis of the Achilles tendon. Early functional conservative therapy using the VARIO-STABIL shoe is a suitable method for treating a newly ruptured Achilles tendon. When there is a precise indication, the method is equally as good as operative therapy and because of the low complication rate, it is even preferable.     

The study of outcomes for CAPD versus hemodialysis patients

Tacrine [1,2,3,4-tetrahydro-9-acridinamine monohydrochloride monohydrate (THA), Cognex] is a potent acetylcholinesterase inhibitor recently approved for treatment of mild-to-moderate Alzheimer's disease. The potential for THA and/or a metabolite of THA to accumulate in brain tissue was investigated by autoradiographic and metabolic profiling techniques in rats given single and multiple doses of [14C]THA. In addition, the brain-to-plasma distribution time course of orally administered 1-hydroxy-THA (1-OH-THA, 24 mg/kg), a primary rat metabolite with anticholinesterase activity, was also examined. Results from a 16 mg/kg single-dose study showed THA to cross the blood-brain barrier readily and concentrate in brain tissue, approximately 5-fold compared with plasma. The metabolite 1-OH-THA was found in much lower amounts relative to THA and when given separately at a similar dose the levels in brain tissue were comparable with plasma concentrations. After multiple-dose administration, THA concentrations in brain tissue were approximately 3-fold higher than those achieved after a single oral dose. However, concentration of 1-OH-THA metabolite increased only 50%. These data suggest a marked difference between the ability of THA and 1-OH-THA to accumulate in brain tissue and may reflect differences in lipophilicity as estimated by calculated log p values. The relevance of THA accumulation in brain tissue to delays observed in THA clinical management of Alzheimer's disease remains to be established.     

Estrogen modulation: tiered testing for human hazard evaluation. American Industrial Health Council, Reproductive and Developmental Effects Subcommittee

Recent concerns about the potential of certain chemicals to modulate estrogen-regulated processes have led to questions as to how chemicals should be tested for such effects. Therefore, AIHC has developed a comprehensive, resource-efficient, and flexible tiered strategy for estrogen modulation (EM) testing. Levels of evaluation include Tier 0, in which exposure, along with alerts based on structure-activity, persistence, bioaccumulation, and other data, are assessed to prioritize chemicals for preliminary testing. In Tier I, short term in vitro, ex vivo, and/or in vivo assays are used to obtain a preliminary indication of EM potential. Among these, an in vivo response assay is considered the most reliable at this time. However, none of these tests are intended for risk assessment, but rather to aid in choosing chemicals for further testing and in guiding the extent of that testing. Tier II is aimed at risk assessment and involves whole animal tests that contain EM-sensitive end points (e.g., two-generation reproduction study). Tier III consists of hypothesis-driven research reserved for situations where targeted research can reduce levels of uncertainty. This tiered approach provides a framework for the strategic and effective application of EM test methods to address specific information needs on a case by case basis.     

Thoracoscopic bilateral lung volume reduction for diffuse pulmonary emphysema

OBJECTIVE: In a prospective study, we investigated the functional results, complications and survival of bilateral video-assisted thoracoscopic (VAT) lung volume reduction (LVR) in a selected group of patients with severe, nonbullous pulmonary emphysema. From January 1994 to September 1996, 42 of 143 candidates (13 female, 29 male, 42-78 years) were operated. They were short of breath on minimal exertion due to severe airflow obstruction and hyperinflation (FEV1 < 30%) pred., TLC > 130% pred., RV > 200% pred.). METHODS: LVR was performed bilaterally by VAT using endoscopic staplers without buttressing the staple lines. Pulmonary function test (PFT), MRC dyspnea score and 12 min walking distance were assessed preoperatively, at 3, 6 and 12 months. In addition lung function was measured at hospital discharge. RESULTS: The patients reported a marked relief of dyspnea, which persisted at all follow-up visits (P<0.001). FEV1 increased from 0.80 +/- 0.24 (L) to 1.14 +/- 0.41 (L) postoperatively, a 43% gain (P < 0.001). A relevant increase of FEV1 persisted for at least 1 year. The residual volume to total lung capacity ratio decreased from 0.64 to 0.56 at hospital discharge. The mean 12 min walking distance increased from 500 +/- 195 (m) to 770 +/- 222 (m) after 1 year (P < 0.001). The mean hospital stay was 13 +/- 5.5 days (median 12.0), drainage time was 9 +/- 4.3 (median 8.0) days. There was no 30 day mortality. Three patients died between 2 and 15 months postoperatively by non surgery related reasons. One patient underwent lung transplantation 5 months after surgical lung volume reduction. CONCLUSIONS: In a selected group of patients with severe, nonbullous pulmonary emphysema, bilateral LVR by VAT results in instantaneous postoperative improvement in pulmonary function and dyspnea. These favorable effects, including an amelioriation in exercise performance, lasted for at least 1 year.