Dominant hereditary conductive hearing loss due to an ossified stapedius tendon

Familial conductive deafness is rare. This report confirms the existence of a lineage with congenital conductive hearing loss in 3 generations. The results of otologic evaluations, including pure-tone audiometry, tympanometry, acoustic reflex test, and liquid test, in 14 patients in this family were consistent with the findings of ossicular fixation in 10 patients. Tympanotomies performed in both ears of 4 patients indicated stapes ankylosis caused by ossification of the stapedius tendon. The patients gained normal hearing levels using a simple surgical procedure.

Perfusion cells for studying regional variation in oral-mucosal permeability in humans. I: Kinetic aspects in oral-mucosal absorption of alkylparabens

PURPOSE

To evaluate regional differences in permeability of human oral mucosa.

METHODS

Newly designed perfusion cells were used for the investigation. The cells were applied to 5 different sites, i.e., dorsum of tongue, ventral surface of tongue, labial mucosa, floor of mouth and buccal mucosa of human volunteers. Model drugs used were methyl-, ethyl-, propyl- and butylparaben, which are passively absorbed from oral mucosa and have different lipophilicities. Biexponential disappearance profiles of the alkylparabens were analyzed kinetically using a two-compartment linear open model.

RESULTS

Both the partitioning parameters to the oral mucosa and the absorption rate constants to the blood circulation correlated to the lipophilicities of the compounds in all mucosa. As to the former parameter, no significant difference was recognized in all mucosa. While, the latter parameter exhibited the regional difference; the absorption rate constants in buccal mucosa were approximately one-half of those estimated in other oral mucosa. A positive relation was recognized between the retention in oral-mucosal compartment and the drug lipophilicity.

CONCLUSIONS

The newly designed perfusion cells used in this study were useful to examine the regional variations of drug absorption from oral mucosa in humans. The absorption rate constant, the partition to oral mucosa and the residence time in oral mucosa increased with lipophilicity of the compound. The regional difference in the drug absorption process was demonstrated; the slow absorption and the prolonged retention were demonstrated in buccal mucosa.

Developmental changes in pharmacokinetics of recombinant human insulin-like growth factor-I in rats

Developmental changes in pharmacokinetics of recombinant human insulin-like growth factor-I (rhIGF-I) were investigated after i.v. administration to rats aged 4 and 7 weeks, as young growing rats and adult rats, respectively. rhIGF-I in the plasma declined multi-exponentially in both groups of rats. Plasma concentrations of rhIGF-I were lower at almost all the time points examined in 4 weeks old rats than 7 weeks old rats. The values of total body clearance (CL[total]) and mean residence time (MRT) indicated that rhIGF-I disappeared more rapidly in 4 weeks old rats than 7 weeks old rats at any dosage. Dose-dependent pharmacokinetics was observed in 7 weeks old rats: the higher the dosage was, the larger the value of CL(total) came to be, but not in 4 weeks old rats. The amounts of IGF-binding proteins (IGFBPs) in the plasma were assessed by determining the endogenous IGF-I, and the levels of the 150 kDa complex, a ternary complex of IGF-I with IGFPB-3 and an acid labile-subunit, were found to be lower in 4 weeks old rats than in 7 weeks old rats. In rats at 4 weeks of age, the elimination of rhIGF-I was significantly faster than for the 7 week old rats, which would be due to the lower plasma levels of IGFBP-3 in young growing rats.

Biopharmaceutical studies on drug/conjugated-metabolite interactions. III. Effect of acetaminophen sulfate and its positional isomers on the pharmacokinetics of acetaminophen in rats

The effect of three positional isomers, o-, m- and p-acetylaminophenyl sulfate (AOAPS, AMAPS and APAPS (acetaminophen sulfate), respectively), on the pharmacokinetics of acetaminophen (APAP) was investigated in rats. All of the intravenously administered positional isomers were rapidly eliminated from plasma, and approximately 80% of the dose was excreted in an unchanged form in the urine within 4 h, while biliary excretions represented a small percent of the doses. Following the intravenous bolus injection of APAP, plasma elimination of APAP was accelerated and the distribution volume of APAP was increased under a steady state concentration (about 10 microg APAP eq/ml) of AOAPS or APAPS, but not AMAPS, as compared with saline infusion. Total body clearances of APAP were increased from 18.3 ml/min/kg for the control to 23.9 and 26.9 ml/min/kg for AOAPS and APAPS coadministration, respectively. AOAPS and APAPS competitively displaced the serum protein binding of APAP, while AMAPS had little effect. The distribution volume of unbound APAP was anomalously increased by APAPS, while it was not affected by AOAPS or AMAPS. Tissue-to-plasma concentration ratios of APAP were significantly increased by APAPS in the liver, kidney and brain, while they were only slightly increased by AOAPS. It was suggested that APAPS has not only the displacing activity of serum protein binding but also other specific effectiveness on the distribution of APAP.

Prediction of the plasma concentration profiles of orally administered drugs in rats on the basis of gastrointestinal transit kinetics and absorbability

A new method based on gastrointestinal transit kinetics has been developed for estimation of the absorption profiles of drugs administered orally as aqueous solutions. The utility of the method was evaluated in rats. The gastrointestinal transit profile for each segment was estimated by in-vivo studies using phenol red, an unabsorbable marker. The gastrointestinal transit profile of phenol red was well explained by a linear gastrointestinal transit kinetic model with eight segments. We also introduced the absorption process into the gastrointestinal transit kinetic model and the plasma profile was predicted by the convolution method. The absorbability of drugs in each segment was assessed by an in-situ absorption study. The validity of the model was evaluated for model drugs with different absorption characteristics. The plasma profiles predicted for ampicillin, theophylline and cephalexin were in good agreement with those observed. The overestimated plasma profile of propranolol suggests that the low bioavailability of propranolol is a result of first-pass metabolism by the intestine wall and the liver, because the calculated absolute absorption is almost perfect. This proposed model is also suitable for estimation of segmental absorption, which is useful for the development of drug delivery systems. We have demonstrated that the plasma profile of orally administered drugs can be predicted by use of gastrointestinal transit and segmental absorbability information and that this method is especially useful for estimating separately the effect of absolute absorption and first-pass metabolism on the bioavailability of drugs.

Solid cerebellar hemangioblastoma with an evolving large cystic component

We present a case of solid cerebellar hemangioblastoma which subsequently developed a large cystic component.

Early squamous cell carcinoma of the lung: CT and pathologic correlation

PURPOSE

To study the factors that influence computed tomographic (CT) visibility of early squamous cell carcinoma, which was defined as a lesion confined to the bronchial wall without lymph node metastasis.

MATERIALS AND METHODS

CT was performed in 18 patients with 18 early squamous cell carcinoma lesions. The 5.0-mm or thinner sections were reviewed independently by three observers who were aware of the bronchoscopic findings, and the visibility of the lesions was correlated with histopathologic findings.

RESULTS

Tumors consisted of 13 flat and five polypoid lesions. Three of the lesions were epithelial, eight were subepithelial, and seven were cartilaginous or extracartilaginous. Eleven lesions were visualized at CT as an endobronchial mass or focal bronchial wall thickening. Lesions with polypoid growth and/or cartilaginous or extracartilaginous invasion were all visualized, even on 5-mm-thick sections. Subepithelial lesions could be demonstrated when located at bronchi with craniocaudal orientation.

CONCLUSION

CT is a valuable tool for diagnosis of early squamous cell carcinomas, particularly when lesions show polypoid growth and/or invade the cartilaginous layer.

Hyperattenuating insulinoma at unenhanced CT

We report a case with insulinoma that showed higher attenuation than normal pancreatic parenchyma on precontrast CT. Pathology of the surgical specimen revealed the presence of psammoma bodies, which were responsible for hyperattenuation. It is worthwhile to obtain precontrast CT in patients suspected of having insulinoma.

Hyperattenuating rim on noncontrast CT of the liver: probable peritumoral sparing of fatty infiltration

CT scans showing a hyperattenuating rim within the liver were retrospectively evaluated in 10 patients to clarify the character, aetiology and clinical significance. All patients had hepatic tumours (7 cavernous haemangiomas in 6 patients, 3 metastatic tumours and 1 hepatocellular carcinoma) as well as fatty infiltration of the liver. Typical features of the hyperattenuating rim on noncontrast CT of the liver included (1) attenuation similar to that of the spleen, (2) a circular or semicircular shape, (3) a width of a few millimeters, (4) peritumoral localization and (5) loss of visualization with contrast enhancement. No such rims were noted around hepatic tumours unassociated with fatty infiltration. Peritumoral sparing of fatty infiltration was inferred. A hyperattenuating rim on noncontrast liver CT, although rare, suggests the presence of a hepatic tumour in fatty liver.

Oral administration of insulin as poly(vinyl alcohol)-gel spheres in diabetic rats

The oral administration of insulin in poly(vinyl alcohol)-gel spheres (PVA-GS), an oral dosage form with prolonged residence time in the ileum, was examined in streptozotocin-induced diabetic rats. Intragastric administration of PVA-GS containing insulin and a protease inhibitor, aprotinin or bacitracin, caused a significant and prolonged reduction of blood glucose levels, suggesting insulin absorption. The bioavailability of insulin estimated from the hypoglycemic effect was about 2% in the presence of either protease inhibitor. The release profiles of insulin and the protease inhibitors from the PVA-GS could be explained by Higuchi's plot, and the rates were similar to each other. The site dependency of insulin absorption in the intestinal tract was examined by an in situ loop method. Insulin absorption estimated by plasma insulin levels was larger in the ileum and the large intestine than in the jejunum. The prolonged residence time of PVA-GS in the absorption site, the lower intestine, and the synchronous release of insulin and the protease inhibitors from the PVA-GS are the two major explanations for the improved bioavailability of insulin administered as PVA-GS containing a protease inhibitor.

Pharmacokinetics of glycyrrhizin in rats with D-galactosamine-induced hepatic disease

The pharmacokinetic behavior of glycyrrhizin (GZ) was examined in D-galactosamine-intoxicated (GAL) rats. When GZ was administered intravenously, the apparent volume of distribution (Vdss) and the total body clearance (CLtotal) were more significantly decreased in GAL rats than those in normal rats. When GZ was administered orally, the area under the plasma concentration-time curve (AUC), the mean residence time (MRT) and the time to reach the maximum plasma concentration (Tmax) for GZ were higher, but the maximum plasma concentration (Cpmax) in GAL rats was lower than that in normal rats. The bioavailability of GZ, however, was not significantly changed. On the other hand, the AUC for glycyrrhetic acid (GA), a main metabolite of GZ, after oral administration of GZ was higher in GAL rats than in normal rats, although there was no significant difference in MRT or Tmax, Cpmax or the bioavailability for GA between GAL and normal rats. The reasons for these differences in GAL rats would be changes in the absorption rate (reduced gastric emptying rate) and reduction of the hepatic elimination rates (biliary excretion of GZ and hepatic metabolism of GA).

Disposition of intravenously administered adenosine 5'-phosphosulfate (APS) in rats

The disposition of adenosine 5'-phosphosulfate (APS), an endogenous nucleotide, was investigated in rats. The degradation of APS in rat plasma was very rapid. APS was degraded in rat plasma to AMP and ATP, and these nucleotides were further degraded through adenosine. The degradation kinetics was examined. For the in vivo study, the method to protect APS from degradation in blood was examined, and it was found that the addition of EDTA to APS-containing blood and storage at 4 degrees C can protect against APS degradation. After intravenous bolus injection, APS in plasma declined rapidly and the rate of elimination was dose-dependent: the biological half-life was about 2s at the dose of 0.3 mg/kg and was longer at 3 mg/kg. When APS was administered by intravenous infusion, the plasma level rapidly reached a steady-state, which then rapidly declined after the infusion was stopped. The total body clearance of APS could not be fully explained by metabolism in plasma or glomerular filtration, therefore the contribution of other elimination processes to the total body clearance was suggested.

Delayed enhancement of peripheral zone of neurofibromas at magnetic resonance imaging

It is well known that bizonal histologic appearance characteristic of neurofibromas are reflected on magnetic resonance (MR) images. We report a case in which a delayed enhanced MR image showed that the entire mass enhanced homogeneously resulting in loss of zonal distinction on early enhanced MR image.

Pharmacokinetics of acetaminophen sulfate after oral administration in rats: analysis of plasma profiles exhibiting a non-linear second peak

The pharmacokinetics of the two-peak plasma profiles of orally administered acetaminophen sulfate (APAPS), a major conjugated metabolite of acetaminophen (APAP), in rats was examined by a two-compartment model having two delivery routes with individual time lags: a direct delivery route of APAPS absorbed in an unchanged form and an indirect one where APAPS was absorbed as APAP after deconjugation in the lower intestine. Pharmacokinetic parameters were estimated by a non-linear least squares program, MULTI(FILT), based on the fast inverse Laplace transform algorithm. Plasma APAPS concentration profiles after oral doses were simulated satisfactorily. In a dose escalation study, the peroral availability of APAPS derived from the direct route was not changed significantly with the doses. However, that from the indirect route was decreased with the dose escalation, suggesting the contribution of a capacity-limited deconjugation of APAPS to APAP by the intestinal microflora to the non-linear pharmacokinetics of orally administered APAPS. The absorption of peroral APAPS in rats at a dose range of 30 to 120 mg APAP eq/kg could be summarized as follows: (1) approximately 25% (22 to 32%) of orally administered APAPS are absorbed from the gastrointestinal tract in an unchanged form; (2) more than 50% (50 to 98%) are deconjugated to APAP in the lower intestinal tract; and (3) the latter plays a significant role as an indirect and non-linear APAPS delivery system because considerable amounts of APAP thus absorbed are rapidly reconjugated to APAPS in the systemic circulation, which gives the second plasma APAPS peak.

Disposition of diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) in rats

The disposition of diadenosine 5'5"'-P1,P4-tetraphosphate (Ap4A), an endogenous dinucleotide, was investigated in rats. The degradation of Ap4A in rat plasma was very rapid and could be explained by a Michaelis-Menten equation: Km and Vmax values were 1.69 micrograms/ml and 4.32 micrograms/min/ml, respectively. Ap4A was degraded in rat plasma to ATP and AMP, but not to 2 ADP molecules, and these nucleotides were further degraded through adenosine. The degradations kinetics were examined. After intravenous bolus injection, Ap4A in plasma declined rapidly and the rate of elimination was dose-dependent: the biological half-life was about 3s at the dose of 1 mg/kg and was longer at 3 mg/kg. When Ap4A was administered by intravenous infusion (0.5 or 1.0 mg/kg/min), the plasma level rapidly reached a steady-state, which then rapidly declined after stopping the infusion.

Segmented areas of increased attenuation in the liver caused by right adrenal tumors: CT features

OBJECTIVE

Our goal was to describe attenuation differences bordered by a straight line in the right hepatic lobe on enhanced CT in patients with right adrenal tumors and to discuss the cause of this appearance.

MATERIALS AND METHODS

Three patients showing attenuation differences bordered by a straight line were discovered in the CT files of 26 cases of right adrenal tumor over 3 cm in diameter. All CT scans were examined by incremental dynamic study.

RESULTS

Two patients had large zone of hyperattenuation in the right lobe bordered with a straight line intersecting both anterior branches of the right portal vein and the inferior vena cava (IVC). A third patient and one of the two patients mentioned already had zones of relative hyper- and hypoattenuation in the medial portion of the posterior hepatic segment, respectively. All three patients had large right adrenal tumors, which severely compressed the right hepatic vein near its confluence with the IVC and/or the IVC in or below its intrahepatic portion. The distribution of attenuation differences was similar to the hyperattenuation at CT arteriography or perfusion defect at CT arterial portography under temporary balloon occlusion of the right hepatic vein and inferior right hepatic vein, respectively.

CONCLUSION

Straight-bordered attenuation differences within the right hepatic lobe at dynamic CT can be caused by compression of the right hepatic vein by large right adrenal tumors.

Gastrointestinal absorption characteristics of glycyrrhizin from glycyrrhiza extract

The differences in gastrointestinal absorption behaviors of glycyrrhizin (GZ) between pure GZ and GZ in glycyrrhiza extract (GE) (equivalent dose as GZ) were examined in rats. Similarly to the case of pure GZ, both GZ and glycyrrhetic acid (GA) were detected in the plasma after oral administration of GE. However, the plasma concentration-time curves of GZ and GA after GE oral administration were much lower than those of pure GZ, indicating the marked reduction in bioavailability of GZ and as GA after this administration. To identify the GE components affecting the absorption of GZ, GZ was removed from GE and the effect of the remaining components on the gastrointestinal absorption process of GZ was examined. The lipophilic components of GE reduced the gastric emptying rate and the absorption of GZ from the small intestine, while these effects were not observed in the hydrophilic components. In contrast, the bioavailability of GZ as GA was increased by the hydrophilic components, but not the lipophilic ones. At least some of the factors in GE altering the bioavailability of GZ were identified.

Fatty mass in the inferior vena cava at CT: lipoma or normal variant?

Fatty mass in the intrahepatic portion of the inferior vena cava (IVC) is an unusual lesion. We describe two cases of fatty mass appearing in the lumen of the IVC on CT and MRI study. We assume that this can be regarded as a benign process, and is mostly a normal variant.

Straight border sign of the liver: spectrum of CT appearances and causes

Attenuation differences bordered by straight lines within the liver (the straight border sign) are sometimes seen at computed tomography (CT). This phenomenon, which was demonstrated with unenhanced CT over a dozen years ago, does not represent a hepatic mass and is often associated with vascular compromise. Major causes of the straight border sign include fatty liver, confluent fibrosis, radiation hepatitis, and vascular abnormalities such as tumor thrombus, thromboembolus, compression, and arterioportal shunt. The frequency of this finding increases when intense contrast enhancement is used, especially when contrast material is administered via the superior mesenteric artery (CT during arterial portography) or hepatic artery (CT arteriography). The use of spiral CT is apparently increasing the chances of encountering this sign in daily practice. To correctly interpret the straight border sign, one should consider the distribution (anatomic vs nonanatomic), the attenuation (low vs high), and the use and technique of contrast enhancement.

Congenital ossification of the stapedius tendon: diagnosis with CT

PURPOSE

To describe the features of congenital ossification of the stapedius tendon at thin-section computed tomography (CT).

MATERIALS AND METHODS

Thin-section CT scans, clinical records, and surgical findings were retrospectively evaluated in nine ears of five patients with surgically proved congenital ossification of the stapedius tendon. Thin-section CT scans of 50 control ears were also reviewed.

RESULTS

On thin-section CT scans, a linear area of soft-tissue attenuation was demonstrated between the monopod stapes and the pyramidal eminence (nine ears), as well as thickening of the stapes footplate (two ears). In the 50 control ears, the normal stapes tendon was not clearly seen on thin-section CT scans.

CONCLUSION

At CT, a linear area of soft-tissue attenuation that extends from the pyramidal eminence to the monopod stapes is suggestive of congenital ossification of the stapedius tendon or a bony bar adjacent to it.

Focal fatty masses of the pancreas

Five patients with solitary fatty mass of the pancreas examined with CT and ultrasound (US) were evaluated. The areas of fat replacement were located in the pancreatic neck, body or tail. The size ranged from 4 to 30 mm in the longest diameter. The shape varied from roundish, to ovoid to semicircular, and the contour was universally well defined. The internal structure was homogeneous in 3 patients, but in one case there were thin septa and, in another, a slightly hyperdense part in the peripheral portion. All the masses except the smallest one were in part contact with pancreatic fat. CT showed fat with the same density as the peripancreatic fat and low HU units. The mass was hypoechoic in 2 cases and hyperechoic in one. The masses in the tail of the pancreas were not detected by US.

Hepatobiliary cysts in patients with autosomal dominant polycystic kidney disease: prevalence and CT findings

OBJECTIVE

Hepatobiliary (intrahepatic and peribiliary) cysts have been described for patients with autosomal dominant polycystic disease. The purpose of this study was to determine the prevalence of these cysts and to describe the wide variation in their appearance on CT scans.

MATERIALS AND METHODS

We studied CT scans for 64 patients (31 men and 33 women) who either had known autosomal dominant polycystic kidney disease or had renal cysts and a family member with polycystic kidney disease. Contrast enhancement was used for 31 patients. CT scans were retrospectively evaluated by consensus by two experienced radiologists. The presence, number, and size of hepatobiliary cysts and the presence and appearance of the two variations, peribiliary and intrahepatic cysts, were analyzed. Peribiliary cysts were determined to be present when many small (< or = 10-mm) cysts were seen adjacent to the larger (up to the third order) portal triad. Cysts present in the hepatic parenchyma but not in contact with the larger portal triad were regarded as intrahepatic cysts.

RESULTS

CT showed hepatobiliary cysts in 56 of the 64 patients (24 men and 32 women; 88%). Intrahepatic cysts were noted in all 56 patients; peribiliary cysts were definitely seen on CT scans for 22 patients and were probably seen (fewer than five cysts and/or cysts located only on one side of the portal vein) on CT scans for 19 patients (73% of all patients with hepatobiliary cysts). Peribiliary cysts appeared as discrete cysts in 31 patients, as a string of cysts in six patients, and as a tubular structure in four patients. Intrahepatic cysts generally were round but occasionally were polygonal. They were variable in number, size, and location.

CONCLUSION

Hepatobiliary cysts were noted in 56 of 64 patients (intrahepatic cysts in all cases and peribiliary cysts in 73% of positive cases). Intrahepatic cysts varied widely in number, size, and location, whereas peribiliary cysts were small and appeared as discrete cysts, a string of cysts, or a tubular structure adjacent to the larger portal triad. It is important to be aware of the wide variety of findings for hepatobiliary cysts so that they are not confused with other abnormalities.