Chondromyxoid fibroma of skull base: a tumour prone to local recurrence.

Chondromyxoid fibroma of the skull base is extremely uncommon. Sometimes involvement of the nasal cavity may occur and the patients may present with nasal symptoms. The biological behaviour of this tumour has not been well studied, primarily because of the limited number of reported cases and the short duration of follow-up. We report a histologically confirmed case of chondromyxoid fibroma of the skull base that recurred repeatedly over a 10-year period after the initial operation. Histologically it showed identical morphology to the original tumour with no evidence of histological progression or dedifferentiation. Ultrastructurally, the spindle tumour cells in the fibromyxoid area showed dual chondroblastic and fibroblastic differentiation, suggesting that these spindle fibroblastic cells and the better differentiated chondroid cells were of the same cell type with different histological morphology.     

The quantification of levator muscle resting tone by digital assessment

The biomechanical properties of the puborectalis muscle are likely to be important for pelvic organ support. However, neither elasticity nor its clinical correlate, muscle resting tone, have received much attention to date. We therefore conducted a prospective study to test a newly developed resting tone scale for validity and reproducibility. Ninety-eight patients underwent a physical examination including prolapse staging and palpation of the levator ani. They were also assessed by 4D translabial ultrasound for levator hiatal dimensions and prolapse assessment. Resting tone was negatively associated with anterior and posterior compartment prolapse. An independent test–retest series yielded a weighted kappa of 0.55 (CI 0.44–0.66), implying “moderate” repeatability. Resting tone of the puborectalis muscle can be determined by digital palpation. It is moderately repeatable and associated with pelvic organ prolapse. Palpation of resting tone may be a useful new tool for assessing women with pelvic floor dysfunction.     

Warfarin-acetaminophen drug interaction revisited.

Physicians and pharmacists routinely advise patients receiving warfarin to take acetaminophen for pain or fever because of its relative safety; however, a recent study questioned the safety of such practice. A comprehensive search of MEDLINE and IPA for human studies and case reports from 1966-1999 revealed evidence that acetaminophen may potentiate the effect of warfarin by a mechanism that has yet to be elucidated. Due to lack of a safer alternative, acetaminophen still should be the analgesic and antipyretic of choice in patients taking warfarin, as long as excessive amounts and prolonged administration (> 1.3 g acetaminophen/day for > 2 wks) are avoided. With the high degree of interpatient variability and the unpredictability of various drug-drug interactions with warfarin, close and frequent monitoring of international normalized ratios is the key for safe oral anticoagulation therapy.     

Incidence, causes and mechanism of hypercalcaemia in a hospital population in Hong Kong

To determine the incidence and causes of hypercalcaemia in a hospital population in Hong Kong, all 29,107 samples received in the laboratory in one year were analysed for plasma calcium and albumin, and samples with a plasma calcium concentration adjusted for albumin greater than 2.55 mmol/l were investigated. Plasma calcium greater than 2.55 mmol/l was found in 462 patients. Repeat samples were received from 302 of these and hypercalcaemia was confirmed in 183. The main causes of hypercalcaemia were malignancy (72.1 per cent), tuberculosis (6.0 per cent), and primary hyperparathyroidism (5.5 per cent). In the malignant hypercalcaemia group, carcinoma of lung was the most common (31.8 per cent) and carcinoma of breast was uncommon (3.0 per cent). Secondary deposits in bone were detected in 35 of the 122 solid tumours. In order to identify the mechanism of hypercalcaemia the contributions of renal tubular reabsorption and increased bone resorption to the plasma calcium concentration were calculated. Increased tubular reabsorption was the main contributor to hypercalcaemia in primary hyperparathyroidism and carcinoma of liver (none of whom had bony metastases) and it contributed significantly to hypercalcaemia in carcinoma of lung without bony metastases and carcinoma of oesophagus. We conclude that in Hong Kong (a) primary hyperparathyroidism is uncommon, (b) tuberculosis is an important cause and (c) humoral factors may be responsible for a relatively high proportion of cases of malignant hypercalcaemia.     

Improved anticonvulsant activity of phenytoin by a redox brain delivery system I: Synthesis and some properties of the dihydropyridine derivatives

Nine chemical delivery systems (CDSs) were synthesized for the efficient transport of phenytoin (DPH) across the blood-brain barrier. The CDSs were based on a dihydropyridine in equilibrium quaternary pyridinium ion redox system which relies on chemistry similar to the NADH in equilibrium NAD interconversion for activity. The chemical carriers, derivatives of trigonelline, 1-alkylcarboxynicotinamide, 3-pyridylacetic acid, and N-methylpicolinic acid, were esterified with 3-(hydroxymethyl)phenytoin. The CDSs proved to be more lipophilic (5-23 times) than DPH. The 1-alkylcarboxydihydronicotinamide CDSs, excluding the sterically hindered one (11e), were quite unstable in rat tissue homogenates and hydrolyzed to release DPH. In human blood, however, they were found to be much more stable (75 times) toward hydrolysis. All other CDSs were oxidized quantitatively to the corresponding pyridinium ion in rat brain homogenates. These compounds were found to possess the required physicochemical characteristics for delivering DPH into rat brain.     

The use of aldosterone-renin ratio as a diagnostic test for primary hyperaldosteronism and its test characteristics under different conditions of blood sampling

Recent reviews recommended the use of the aldosterone/renin ratio (ARR) to screen for primary hyperaldosteronism. However, widely different cutoff levels have been proposed, and test characteristics of ARR under different conditions of sampling are not known. We conducted a retrospective review among 45 subjects with carefully validated diagnoses of primary hyperaldosteronism and 17 subjects with essential hypertension to study the utility of ARR. Sixty-two patients with 75 sets of plasma renin activity (PRA), aldosterone, and ARR values from a postural study and 48 sets of values from a saline suppression test were analyzed. Ninety-four percent of these subjects underwent investigations because of hypokalemic hypertension.ARR yielded larger areas under the curve in the receiver-operating-characteristics curve than PRA or aldosterone under all conditions of testing. Our results confirmed the superiority of ARR to either aldosterone or PRA alone as a diagnostic test for primary hyperaldosteronism.ARR cutoff levels were significantly affected by the condition of testing. Depending on posture and time of day, it varied from 13.1-35.0 ng/dl per ng/ml.h in our study population. When using ARR for screening primary hyperaldosteronism, posture and time of sampling should be standardized both within and between centers to minimize variability in cutoff levels.     

Quality of life in a random sample of community dwelling older patients with essential tremor

STUDY OBJECTIVE - Nested case-control study aimed to assess the quality of life of community dwelling participants aged 65 years or over with newly diagnosed Essential Tremor (ET). METHODS AND RESULTS - Thirty-two participants with newly diagnosed ET and 32 age and gender matched controls were administered the Rand-SF36 quality of life questionnaire. Medical co-morbidities were also assessed in the two groups. Results - Participants with ET had significantly lower scores in the physical function, role limitation because of physical function, role limitation as a result of emotional problem, pain, and energy/vitality subscales of the Rand-SF36 when compared with controls. CONCLUSIONS - Older patients with newly diagnosed ET have poorer quality of life than their community dwelling counterparts without ET.     

Sarcomatous transformation in diaphyseal aclasis

Multiple hereditary exostosis (or diaphyseal aclasis) is a condition characterized by the development of multiple osteochondromas. The tendency for malignant transformation into chondrosarcoma is well known. Malignancy typically arises from the cartilaginous cap of the osteochondroma. Radiographs supplemented by computed tomography have an important role in the diagnosis of this condition. Magnetic resonance imaging shows the features of sarcomatous change and aids in differentiating malignancy from pseudotumours.