Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography

The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.     

Estimating profits in a capitation program. Planning for cost

This article is designed to help dentists make better decisions regarding capitation programs. It focuses on approaches to costs that can be useful. An example is given that illustrates how these cost concepts might be used to analyze a capitation proposal.     

Maxillary sinusitis in adults: an evaluation of placebo-controlled double-blind trials

BACKGROUND: In general practice, acute sinusitis is frequently diagnosed and treated with antibiotics. OBJECTIVE: This study aimed to determine the evidence for the effectiveness of antibiotic treatment in acute maxillary sinusitis in adults by assessing the methodological quality of placebo-controlled double-blind randomized trials. METHOD: An evaluation by four raters through a 35-item scoring-scale for internal and external validity of all placebo-controlled double-blind randomized trials on acute sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five trials were excluded because they were not placebo-controlled, double-blind, randomized, or were carried out in patients with chronic sinusitis or in children. The three remaining trials were performed in different populations (one in general practice) between 1973 and 1978. Only one study claimed superiority of antibiotic treatment. Different inclusion criteria and major outcome measures were used by the authors. The reliability of major outcome events was reported poorly or not at all and in two studies outcome measures were clinically inappropriate. The studies scored 30-62% of the maximum attainable score for internal validity and 10-20% for external validity. CONCLUSION: The effectiveness of antibiotic treatment in acute maxillary sinusitis in a general practice population is not based sufficiently on evidence.      

Studies in Red Blood Cell Preservation. 8. Liquid Storage of Red Cells in a Glycerol-Containing Additive Solution

The purpose of the present study was to determine whether a hypotonic additive containing a low concentration of glycerol as a membrane permeable solute would improve the liquid storage of red blood cells (RBCs). Packed RBCs were stored either with 200 ml of an experimental additive solution, EAS 25, containing (m M ): glycerol 150, adenine 2, glucose 110, mannitol 55, and NaCl 50, or with 100 ml/unit of a conventional additive solution Adsol®. The results show that the adenosine triphosphate values, hemolysis, potassium leakage, and the morphology scores of RBCs were significantly better with EAS 25 than with Adsol up to 84 days of storage. The ATP values were significantly different only after the first 42 days of storage. The mean corpuscular volumes (MCVs) of the RBCs were significantly higher throughout in the experimental additive accompanied by decreased microvesiculation as compared to Adsol. The total microvesicle membrane protein shed by 100 ml of RBCs was 47.92±12.31 mg in Adsol and 18.96±5.49 mg in EAS 25 (p<0.001). The larger MCVs of the RBCs in EAS 25 may have a favorable effect on maintaining membrane integrity by decreasing the loss of membrane by microvesiculation.     

Oral premedication in children

Preoperative and postoperative sedation, postoperative analgesia and vomiting were assessed following four different oral premedications in 143 children aged 1-10 years, weighing 10-30 kg, and undergoing elective adenotonsillectomy or inguinal surgery. Diazepam, diazepam combined with droperidol, trimeprazine and trimeprazine combined with droperidol were compared in a double-blind trial in conjunction with a standardised inhalational anaesthetic technique employing an intraoperative narcotic. Trimeprazine produced significantly more preoperative sedation (P less than 0.001) and was associated with enhanced postoperative analgesia (P less than 0.01). The incidence of postoperative vomiting was significantly less in the group receiving trimeprazine (P less than 0.001). The addition of droperidol to diazepam and trimeprazine only marginally improved the performance of those drugs but significantly prolonged postoperative recovery times. This was more marked when droperidol was combined with trimeprazine.     

An analysis for menstrual data with time-varying covariates

This paper concerns the analysis of menstrual data; in particular, methodology to identify variables that contribute to the variability of menstrual cycles both within and between women. The basis for the proposed methodology is a parameterization of the mean length of a menstrual cycle conditional upon the past cycles and covariates. This approach accommodates the length-bias and censoring commonly found in menstrual data. Data from a longitudinal study of menstrual patterns and other variables among Lese women of the Ituri Forest, Zaire, illustrate the methodology. A small simulation illustrates the bias caused by incorrectly deleting the censored cycles.     

Convergence of occipital nerve and superior sagittal sinus input in the cervical spinal cord of the cat

Co-existence of facial and occipital pain may occur in occipital neuralgia, migraine and cluster headache; suggesting convergence of trigeminal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In anaesthetized adult cats, the superior sagittal sinus and occipital nerve were stimulated electrically, and extracellular recordings made in the dorsolateral area of the upper cervical cord using glass-coated tungsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had superior sagittal sinus input and 3 (6%) had occipital nerve input. Convergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and superior sagittal sinus on dorsolateral area units in two-thirds of cases studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches.     

Nonsteroidal anti-inflammatory drugs (NSAIDs) and the kidney

In patients with PG-dependent renal function, NSAID administration constantly reduces GFR and RBF in a dose-dependent fashion. In this situation, the risk of overt acute renal failure is high and should be taken into proper account. In contrast, the incidence of NSAID-related renal structural alterations appears to be very low, yet the absolute number of patients may be significant considering the wide use of such drugs. Concerning the antiproteinuric effect of NSAIDs, the unfavourable ratio risk/benefit does not seem to support their indication in proteinuric nephropathies. The development of PGHS-2 selective inhibitors is promising, and may open new therapeutical strategies in the treatment of the progression of renal disease.