No volume effect on retrograde colonic spread of rectally-administered ropivacaine gel.

BACKGROUND: Rectal administration of enemas, foams and suppositories is the most efficient way to deliver locally acting drugs to the distal colon. Ropivacaine, a long-acting local anaesthetic, was chosen as a candidate for a new rectal treatment of ulcerative colitis. AIM: To determine the colonic spread of a rectal ropivacaine formulation. METHODS: In this randomized, incomplete cross-over study, 12 male volunteers were given 200 mg ropivacaine HCl rectally in 20, 40, 60 and 80 mL hydroxypropyl methylcellulose gel. The viscosity of the gel was 1.1 Pa s. The spread of the radiolabelled (99mTc-labelled diethylenetriaminepenta-acetic acid) formulations was assessed by gamma-scintigraphy. Plasma was collected and analysed for ropivacaine base. RESULTS: The retrograde spread was limited to the descending colon and the difference between the studied volumes was not statistically significant. Only the 80-mL volume tended to have a larger distribution, although the 20-mL volume showed the same maximal distribution in two subjects. No distinct relationship between volume, retrograde colonic spread and plasma concentrations could be found. Ropivacaine was well tolerated. CONCLUSIONS: Rectal ropivacaine gel in all volumes between 20 and 80 mL can spread up to the descending colon. There was no relationship between either retrograde colonic spread or the administered volume and the ropivacaine plasma concentrations.

V/Q distribution and correlation to atelectasis in anesthetized paralyzed humans.

Regional ventilation and perfusion were studied in 10 anesthetized paralyzed supine patients by single-photon emission computerized tomography. Atelectasis was estimated from two transaxial computerized tomography scans. The ventilation-perfusion (V/Q) distribution was also evaluated by multiple inert gas elimination. While the patients were awake, inert gas V/Q ration was normal, and shunt did not exceed 1% in any patient. Computerized tomography showed no atelectasis. During anesthesia, shunt ranged from 0.4 to 12.2. Nine patients displayed atelectasis (0.6-7.2% of the intrathoracic area), and shunt correlated with the atelectasis (r = 0.91, P < 0.001). Shunt was located in dependent lung regions corresponding to the atelectatic area. There was considerable V/Q mismatch, with ventilation mainly of ventral lung regions and perfusion of dorsal regions. Little perfusion was seen in the most ventral parts (zone 1) of caudal (diaphragmatic) lung regions. In summary, shunt during anesthesia is due to atelectasis in dependent lung regions. The V/Q distributions differ from those shown earlier in awake subjects.

Preoperative radiographic evaluation of implant sites by computed tomography. Radiation dose profiles.

The purpose of the present study was to compare radiation dose profiles for one and two mm slice thicknesses typically used for preoperative computed tomographic examination of potential implant sites. A Siemens Somatom DRH CT-system was used. A single two mm slice absorbed only 29% of the integral dose and a single one mm slice, absorbed only 17% of the integral dose. This is because the radiation beam was unchanged between the two different examinations. The integral dose is therefore identical for a single one mm slice and for a single two mm slice. When 10 consecutively two mm thick slices were exposed, approximately 50% of the integral dose was absorbed within the examined region. When 20 one mm thick slices were exposed, slightly less of the integral dose was absorbed within the examined region. This difference may be explained by uncertaines in the measuring instruments. The integral dose is, with the 10 two mm thick slices, half the integral dose compared to a serie of 20 one mm slices. In spite of a well restricted beam, more than half of the integral dose is absorbed outside the examined part. Consequently, during examination the thyroid gland, the eyes lens and the pituitary gland will be exposed to some irradiation.

Basic technical properties of a system for direct acquisition of digital intraoral radiographs.

The Sens-A-Ray system for direct digital intraoral radiography may be used with any computer compatible with an IBM PC/AT. The system relies on a charge-coupled device designed for direct conversion of x-ray energy to an electronic signal. It is the first such device for direct acquisition of radiographs. Technical properties of charge-coupled device detectors when exposed to radiation energies in the range of x-rays used in dental radiography have been studied. Even in the absence of light or x-radiation there is a spontaneous generation of charge within a charge-coupled device detector that gives rise to a background signal, a dark current. It was found that the dark current is a linear function of exposure time. The dose response of the charge-coupled device detector was determined at nominal kilovoltages that range from 50 to 90 kVp. The dose response was shown to be a linear function of exposure. The functions for all kVp settings were practically identical. The charge-coupled device detector is more sensitive to x-radiation than conventional dental films and, consequently, its exposure range is more narrow. The signal-to-noise ratio was calculated from the digital radiographs used for the dose response test. The ratio is above 10 for exposures higher than about 2 microC/kg. The line spread function was determined from test radiographs of a 10 microns wide slit in a test object of 1.5 mm thick tantalum. After curve fitting, the line spread function could be expressed as the sum of a Gaussian and an exponential function. Presampling modulation transfer functions valid at the detector plane and at an object plane were calculated from fitted data on the line spread function. It is concluded that the Sens-A-Ray system has such technical properties that it may replace conventional film-based systems.

Effect of ursodeoxycholic acid treatment on ileal absorption of bile acids in man as determined by the SeHCAT test.

The effects of urodeoxycholic acid on ileal absorption of bile acids and on serum bile acid and lipoprotein concentrations were studied. Eight healthy subjects were investigated. The gamma emitting bile acid analogue, SeHCAT, was given orally and its fractional catabolic rate and seven day retention were assessed by repeated external counting over the upper abdomen during the next seven days. Ursodeoxycholic acid was then given orally at a dose of 15 mg/kg/day for three weeks and the study was repeated during treatment. The fractional catabolic rate increased by 64% (mean (SD), 0.333 (0.159) v 0.203 (0.061)/day; p less than 0.05) and seven day retention decreased by 44% (15(10) v 27(10)%, p less than 0.001), indicating bile acid malabsorption. Total serum cholesterol fell from 5.79 (1.22) to 5.50 (1.18) mmol/l (p = 0.05), while serum ursodeoxycholic acid increased 22 fold (7.87 (2.67) v 0.34 (0.24) mumol/l, p less than 0.001). Five of the subjects continued taking 30 mg/kg/day of ursodeoxycholic acid for one week and showed an increase in fractional catabolic rate of 81% (0.300 (0.091) v 0.166 (0.037)/day; p less than 0.05) and a fall in seven day retention of 50% (16 (12) v 32 (8)%, p less than 0.01). There were significant reductions in total cholesterol (5.36 (1.71) v 6.08 (1.47) mmol/l; p less than 0.05) and low density lipoprotein cholesterol (3.70 (1.33) v 4.58 (1.16) mmol/l; p less than 0.05). The results support the concept tht ursodeoxycholic acid treatment interferes with the absorption of endogenous bile acids, and emphasise the beneficial effects of this treatment of lipoprotein concentrations in man.

Improved portal film image quality in radiation therapy with high energy photons.

Various metal screen-film combinations have been investigated in order to determine the best radiographic image. The quality of these different combinations has been evaluated by measuring the scattered to primary film dose ratio S/P. The S/P ratio increases with increasing atomic number of the front screen for 4 MV x-rays but shows no significant difference for 8 MV x-rays. For rear screens the S/P ratio is slightly increased for higher atomic numbers. A metal with an atomic number around 26-29 should be an optimal metal screen regarding quality aspects. A cassette of stainless steel has, in clinical use for portal and/or verification films, given very good images.

Experimental obstructive hydronephrosis in newborn rats. XI. A one-year follow-up study of renal function and morphology.

Partial obstruction of the left ureter was created in two-day-old rats and its effects on kidney function were studied with 99mTc-DMSA and 99mTc-DTPA after one, two, three and six weeks, and after one year. Kidneys from animals sacrificed at the age of six weeks or one year were also examined histologically. The obstructed renal pelvis was enlarged by about 35 times and there was a delayed excretion of 99mTc-DTPA during forced diuresis, indicating significant, chronic obstruction. The renal DMSA-uptake ratio (left kidney/(left and right kidney] was reduced to about 40% from the first week of obstruction. The parenchymal weight ratio (expressed as above) was reduced to about 45% after both six weeks and one year. The glomerular filtration rate, examined during forced diuresis and calculated on the basis of uptake capacity, was lowered to 42% after six weeks but was not significantly reduced after one year of obstruction. The incidence figures for medullary hemorrhage or accumulation of iron pigment, and chronic inflammatory changes in the cortex were somewhat higher after one year of obstruction than after 6 weeks, but the lesions were patchy in both groups. We conclude that partial unilateral ureteric obstruction, created in the neonatal period, leads to a slight but permanent functional disturbance and parenchymal weight reduction without prominent structural parenchymal damage.