The inhibition of calcium oxalate monohydrate crystal growth by maleic acid copolymers

The crystallization of calcium oxalate monohydrate (COM) was investigated at conditions of constant supersaturation both in the absence and in the presence of synthetic maleic acid copolymers at 37C, 0.15 M NaCl. The dependence of the rates of COM crystallization in the absence of inhibitors was found to be second order at low and first order at higher supersaturations suggesting a surface diffusion controlled mechanism. The presence of all copolymers tested at concentration levels up to 5 ppm retarded the rates of COM crystal growth up to 90%. The decrease of the COM crystal growth rates by the polymers depended on the nature of the comonomer polymerized with maleic acid and the order of inhibition was found to be vinyl acetate > N-vinylpyrrolidone > styrene. Taking into consideration kinetics data published in the literature concerning the inhibition of COM crystal growth, it is suggested that molecular weight also plays a role, with more inhibition at higher molecular weights. The morphology of the COM crystals grown was unaffected yet the crystals growing at lower rates in the presence of the copolymers were larger and their size more uniform. It is concluded that maleic acid copolymers are strong inhibitors of the crystallization of COM, the inhibitory activity being more pronounced in the case of the linear copolymers.     

Impact of scale standardization on images of digital radiography systems

OBJECTIVES: To test the effect of altering image size on diagnostic quality. METHODS: Endodontic files, size 10 and 15 were prepared to full root length and 1.5 mm short, in upper and lower molars and premolars. Digital images of the Sidexis (S) and Visualix/Vixa (V) system were reduced in size to Digora (D) scale, and the D images were enlarged to S scale. ROC analysis was performed and data analysed with MANOVA statistics. RESULTS: Assessment of root canal length with file size 10 was less accurate for the S images reduced in size, compared with the original S images (P < 0.011). All other differences were not significant (P > 0.081). CONCLUSIONS: Relevant diagnostic information may be lost when images are reduced in size. Therefore, for optimal presentation, the smaller images should be enlarged rather than the larger ones reduced.     

Tuberculosis meningitis in Hong Kong: experience in a regional hospital

Tuberculous meningitis (TBM) remains common in Hong Kong. From January 1996 to June 1997, 11 adult patients with TBM presented to Queen Mary Hospital, a regional hospital in Hong Kong. The annual incidence of TBM was estimated at 1.8 per 100,000 population. Nine patients were local Chinese, and only one patient had the acquired immune-deficiency syndrome (AIDS). In contrast to the classical presentation as a chronic indolent disease, our patients presented acutely: the mean duration from onset of symptoms to presentation was 4.8 days (range 0-10). The most common presenting symptoms were headache (64%), fever (46%), or both (36%), with focal deficits occurring in 64% of patients. Cerebrospinal fluid (CSF) culture and polymerase chain reaction (PCR) were positive in 30% and 29% of cases. Mean CSF cell count, protein and glucose levels were 340 x 10(6)/L, 267 mg/dL, and 2.3 mmol/L, respectively. Extra-neural tuberculosis occurred in 46% of cases. All patients survived and responded to treatment. Drug-induced hepatotoxicity was common; 64% of patients developed biochemical hepatitis.     

In vitro encystment and experimental infections of Blastocystis hominis

Cultures of Blastocystis hominis were induced to encyst using three encystation media: (a) an encystation medium (EM) comprising yeast extract in buffered saline containing 50% horse serum, (b) an encystation medium (CEM) comprising EM conditioned with bacterial soluble products and (c) an encystation medium (TEM) containing 0.5% trypticase in EM. Two isolates of B. hominis were studied, an axenized isolate C and a non-axenized isolate MS. In EM, isolate C did not encyst, whereas 6.1% of isolate MS had encysted by day 1. However, in CEM and TEM, 17.4% and 25.7% of isolate C, respectively, had encysted by day 5. In all three media, isolate MS encysted more readily than isolate C, with as much as 91.7% of the former encysting in TEM. As viewed by phase-contrast microscopy, cyst-like stages appeared highly refractile. Direct stool examination of juvenile Wistar rats infected with 10,000 cyst-like stages of both C and MS isolates showed Blastocystis at day 2 post-infection. At autopsy on day 7, large numbers of Blastocystis were seen in the cecum, with smaller numbers being observed in the large intestine. In contrast, rats fed with various inocula of the vacuolar stages of isolates C and MS did not become infected, indicating the importance of the encysted stages in the transmission of the parasite.     

Think-aloud approaches to cognitive assessment and the articulated thoughts in simulated situations paradigm

In addition to widely used endorsement methods, one way to get at people's thoughts is to have them verbalize while engaged in a task or situation. The articulated thoughts in simulated situations (ATSS) paradigm is a think-aloud approach to cognitive assessment that has several advantages: an unstructured production response format, on-line rather than retrospective assessment, situational specificity and control, and flexibility of situation and cognitions. The authors review experiments that have examined articulated thoughts in clinically relevant contexts. ATSS does have certain limitations and further research into its psychometric properties is needed, but it seems promising as a versatile and adaptable method of cognitive assessment, especially when little is known of the cognitive terrain of interest.     

An investigation of factors associated with fluid adherence among hemodialysis patients: a self-efficacy theory based approach

Three cases of mediastinal neurogenic tumors originating from the intrathoracic vagal nerve is reported. Two of those is neurilemmomas. One tumor was located in the site to the branching point of the recurrence nerve. The tumor was enucleated. Postoperative hoarseness arose. Another tumor was located in the vagal nerve. The tumor was resected. One of those is neurofibromatosis in the vagus nerve with the axillary tumor. The tumors arose from the vagus nerve was resected. Careful follow-up are required in two patients.     

The effects of self-hypnosis on quality of life following coronary artery bypass surgery: preliminary results of a prospective, randomized trial

The effects of complementary techniques and alternative medicine on allopathic therapies is generating much interest and research. To properly evaluate these techniques, well controlled studies are needed to corroborate the findings espoused by individuals practicing complementary medicine therapies. To this end, we evaluated the role of one of these therapies, self-hypnosis relaxation techniques, in a prospective, randomized trial to study its effects on quality of life after coronary artery bypass surgery. Subjects were randomized to a control group or a study group. Study group patients were taught self-hypnosis relaxation techniques the night prior to surgery. The control group received no such treatment. Patients then underwent routine cardiac management and care. The main endpoint of our study was quality of life, assessed by the Profile of Moods Scale. Results demonstrated that patients undergoing self-hypnosis the night prior to coronary artery bypass surgery were significantly more relaxed than the control group (p = 0.0317). Trends toward improvement were also noted in depression, anger, and fatigue. This study demonstrates the beneficial effects of self-hypnosis relaxation techniques on coronary surgery. This study also identifies endpoints and a study design that can be used to assess complementary medicine therapies. Results of this preliminary investigation are encouraging and demonstrate a need for further well-controlled studies.